I agree about AUs in general, but not about all AUs. Canon divergence and setting AUs are a big part of fanfic culture. AUs which create a whole alternate system of reproduction and discrimination are not.

If you're in Supernatural RPF fandom, which originated omegaverse, maybe it's common enough to be a huge risk. In most fandoms, things like omegaverse and hanahaki or whatever crazy biologically deterministic AU is rising in some other fandoms, are not the same.