Everyone is responsible for the overall health of the game
That means everyone is responsible for finding a place for themselves and their characters within the game. If the game is focused overcoming an extremely challenging tactical position and saving the world despite the massive resources and power of your opponents, then it may be that a certain amount of power is mandatory for a character to participate. And if that’s the case, then it is the individual responsibility of every participant to ensure that they come to the table with a character that fits within that game.
Likewise, if a game is focused on the social interactions of the characters within the society of the town, and violence is all-but-verboten as a solution to problems, then it may be mandatory for every character to have a deep enough background, with fleshed-out social connections to the town, in order to play. It becomes every player’s responsibility to come to the table with such a character.
Characters from the first game won’t fly in the second game, and vice versa. A character with no backstory and whose only notable feature is the ability to one-shot-kill a god might be entirely appropriate for the first, but utterly inappropriate for the second. That character would, most likely, be rejected by that society and thus unable to participate. A character with tons of influence and social standing, but with no survival skills or combat ability, sounds like a perfect fit for the second, but would not be appropriate in the first. That character would be one of the people the first group are trying to protect, and would be left behind in whatever safety is available, and would not be able to participate.
No one has a right to play whatever character they want, the expectations of the game and table be damned. It is every player’s responsibility to come to the table with something that fits the game.
The problem comes when you have games that aren’t as clear-cut as my two examples—and you have people at the table disagreeing about what sort of game it is. When you have an epic quest to save the world, making friends along the way, one player might see this as closer to the first game, while another might see it as closer to the second. This doesn’t have to be a problem, of course—the really important thing is that everyone enjoys the game, so as long as everyone gets an appropriate amount of time in the spotlight, and there are situations where both players’ characters can shine, there isn’t a problem.
So in the end, it becomes a question of what kind of game does everyone want to play, or think they are playing? Is everyone on the same page? If not, is the DM comfortable catering to both as appropriate, and is everyone comfortable with there being segments of the game that perhaps interest them less or interact with their character less?
If you want to play a lower-power character, are you accepting that you are lower-power, and so will have less opportunities to shine in hard mechanical situations? Or are you demanding that everyone else get to the same place as you, just so you can play the character you want? The former is fair and reasonable; the latter is not.
If you want to play a higher-power character, are you accepting that you are higher-power, and the game will have segments where that does not matter and that will highlight what the other characters have going on? Or do you want your optimization to mean you “win” and get to have the spotlight on you all of the time? The former is fair and reasonable; the latter is not.
In the specific case of you wanting to play a lower-power character, and other players objecting to the character on the grounds that it is too weak, that needs to be the discussion that you are having: is this a game that mandates higher-power than your character is offering? And if the other players think it is, why do they think that—what are they concerned about losing if the game is tweaked to allow your character to participate? Note that there are valid concerns that might exist here. It’s not the case that they are simply wrong—it might be, but it also might not be. You have to be open to that, because you have a responsibility to engage with the premise of the game and this is part of it.
- Other players might—reasonably—point out that their characters couldn’t, in good conscience, bring someone as vulnerable as your character along on their quest.
- Alternatively, they may simply be interested in greater mechanical challenges, and be worried that the presence of a lower-power character will require the DM to water down the challenges, or force one of the higher-power characters to “babysit” the lower-power character.
- If the game has a “master” player, who is responsible for the challenges the party faces, that player may well object to the simple power disparity as making their job too difficult.
And so on. You can discuss these, determine if these—or others—are concerns that the other players have, and then determine whether or not those concerns are valid in the particular case of the game you are all seeking to play. If they are valid, you can consider how they could be remedied—whether it means a different character, or tweaks to the system to allow the same character to move upward on that graph you have, or whatever else.
But nobody has a “right” to play. This is a voluntary, cooperative activity for fun—your ability to participate is entirely predicated on the voluntary cooperation of those you would play with. You can’t make them play something they don’t want to play; they can’t make you play something you don’t want to play. The only way anyone gets to play is if everyone gets along and agrees to play—and agrees to play the same game. That’s all it really comes down to.