The root cause is a failure to understand that Actions are not all-encompassing.
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The rules list 5 activities that you can do [On Your Turn][1]:
>On your turn, you can move a distance up to your speed and take one action. 

>**Bonus Actions**

>Various class features, spells, and other abilities let you take an additional action on your turn called a bonus action.

>...

>**Other Activity on Your Turn**

>Your turn can include a variety of flourishes that require neither your action nor your move.

>You can communicate however you are able, through brief utterances and gestures, as you take your turn.

>You can also interact with one object or feature of the environment for free, during either your move or your action.

>...

>**Reactions**

>Certain special abilities, spells, and situations allow you to take a special action called a reaction. A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's.

**To reiterate, the 5 activities are:**

 1. Move
 2. Actions
 3. Bonus Actions (which are not a type of 'action')
 4. Other Activities (a class containing all miscellaneous activities) including;
  - Brief communication
  - Object interaction
  - Broadly, anything that "does not require an action"
 5. Reactions (with a note that they can be used on someone else's turn).

Of these activities only 1 of them is an "Action". This confusion and resulting mistaken assumption that everything you do on your turn is an Action has lead to a lot of fundamental misunderstandings about how 5e works.

A special note for Bonus Action:
--------------------------------

Bonus Actions are not Actions. They let you take an Action, usually from a select list. "Let" means you have the option, you are allowed to. It does not mean that Bonus Actions _are_ actions.

  [1]: https://www.dndbeyond.com/sources/basic-rules/combat#YourTurn