It can easily backfire. Some one who has an urgent but basic question might refrain from speaking up if, beforehand, a senior prefaces their pointed probing question with "this is a stupid question...".

It's better to just kick things off with naive questions or even use a bit of humor to disarm people, so they don't feel like they have to be "advanced" all the time.

You don't say this is. You say "this may be" a stupid question.

The point is not that anyone with the same question should feel stupid; it's that I don't care if anyone thinks I am.

Depending on who is asking, the intention behind such framing is different. For someone in a leadership position, the point is to open up dialog and make folks comfortable enough to ask questions without them feeling they're at risk of humiliation or judgement. For others it may be to signal politeness and deference to the speaker.

Whatever the case, there are more effective, more genuine phrasings to use than to literally invoke "stupidity".

> more effective, more genuine phrasings

Examples please?

I was thinking about:

"I'd like to ask some things that might be obvious to many of you: ..."