The "Vicissitude could replace surgery..." assumption came up frequently from various fans and informal discussions during the older editions. However, the rules didn't ever directly state that Vicissitude could be used for beneficial medical purposes, and definitely didn't allow one to remove wound levels from a character's health track. There were many depictions in the source books of Vicissitude accomplishing effects akin to plastic surgery and body modifications. Although surgery, these don't heal the target.
Tzimisce first appeared as NPC antagonists when the Sabbat were introduced. Vicissitude and its effects were given a vague description that STs could use, but no firm rules (same for Lasombra and Obtenebration). They became playable and got full Vicissitude rules in Players' Guide to the Sabbat, a 2nd Edition supplement.
Players' Guide Vicissitude 2 implies that healing is not possible:
Fleshcrafting provides no special benefit to the subject other than a
Players' Guide Vicissitude 3 makes no mention of healing, and specifically can be used for damage:
If Bonecraft is used deliberately without Fleshcraft for the purpose of inflicting injury, the victim takes on die of damage for each success the crafter rolls
Self-healing appears in Elder-levels of Vicissitude in various editions, such as Level Ten, Reform Body in Players' Guide. These powers tend to be offshoots of Blood Form type abilities, wherein the Tzimisce has mastered its own body and vitae enough that they are basically one and respond to the character's will. These abilities have never been able to target other characters.
The V20 Dark Ages rules were written after a lot of player community review and feedback, and the writers had already been watching forums discussions on the game. Because players kept asking about or advocating for the "Vicissitude could replace surgery..." idea the V20 Dark Ages rules were written to dispel this notion.