This question

is basically just a statement of a few conjectures by the asker. The "question" is just "What do you think?"

It's not clear what kind of answer can anyone expect for a question like this. (Are we supposed to resolve the conjecture and post the answer on MO? Are we supposed to give hints? When the conjectures are new and due to the asker, then we probably can't point to anything in the literature.)

The conjectures in the linked question are (in my opinion) kind of nice, and deserve a nice home, but is MathOverflow the right place for them? If so, then is "what do you think?" a good way to post conjectures on MO? If not, then what?

This seems separate from the cases discussed in What should be the policy on "open problems" on MO?, which seems more concerned with questions about existing, well-known or not so well-known, open questions, rather than new conjectures formulated by the asker.

The help (https://mathoverflow.net/help/on-topic) has the line "If you want to contribute to (or view) a list of open problems, visit the Open Problem Garden."

So it seems to me that MO questions aimed at introducing and publicizing new conjectures are at least somewhat discouraged and redirected to the Open Problem Garden. But this seems to be unenforced. It could be much more clear.

My concern is that if everyone started posting their conjectures like "here's a conjecture, what do you think?" then... well, it wouldn't be the end of the world, but it would be a pretty noticeable change in MO, and I don't know if people would want that. I for one have several incredibly dull conjectures...

If I'm on the right track, then some possible actions might be to strengthen language in the help doc, and add a flag for off-topic due to conjecture. Maybe something like "MathOverflow is for mathematicians to ask each other questions about their research. See Open Problem Garden to publicize conjectures in mathematics."