This is just growing pains for a new industry. OpenAI shot up to 100M users almost overnight. Hosting AI models at that scale has never been done before, and surely was costing them a fortune. It's not surprising to me they are futzing around with things and causing some regressions.
Yes self-hosting is one option, and probably a good one for many companies. But I also suspect OpenAI and AI APIs by others will get much more stable and reliable in the coming months and years as the industry matures and best practices are adopted.
I would guess AI API reliability and maturity will asymptotically approach that of other cloud services, like S3, as more and more things depend on them.