Is that just a meme response now or is there more to it?
The market (and technology) is very immature. We have no idea what potential usecases, integrations, or models will ultimately dominate. Even if there is a single one-model-to-rule-them-all there is still going to be potential for smaller/almost-as-good models to be succession by doing direct integrations with various business or B2C usecases.
The chatbot UI is just one potential usecase that's popular now. That might have dominance in pure brand recognition and userbase, but it's not like they have network-effects or other lock-in either (besides maybe custom API integrations).