You need to turn down your suspicions.
Can't ask questions without drawing the wrath of some users here...
Anyway:
I thought about it but in the end went with Bitwarden just because it's convenient and didnt feel like entering the security minefield.
Same was for pictures (kept them on my PC and that was backed up to another drive) and E-Mail.
As my gear improved I started to use Immich.
E-Mail is still outsourced as I can't and don't want to deal with getting put on spam-lists and having to deal with getting of of it (had the pleasure of getting my domain already marked by google safe browsing).
The "gotcha" about conflicting (as you put it and trying to infer further bad faith conversations) was more about edge cases biting you in the ass.
Not fun having to search accounts if you expect them to be securely saved in the vault but not being there.
Anyway, the point of my question was to understand why people use a cloud service for this when it can be easily done (and be safer) than relying on a 3rd party cloud. From what I can tell it's "convenience".
That's mine and being under the assumption a corp that is specializing and programming a security product is probably better at it than me.
And so far the behavior from Bitwarden after being audited and their current breach-history gives me enough faith for now.
They had some oof-moments like master-password are used to encrypt the vault and weak encryption protocols with weak encryption parameters on top
But they werent enough to start a transition elsewhere.