The people who switch back and forth between providers every month are a very small, but loud, minority.

OpenAI did pull ahead in limits and quality for a while. Anthropic took it back with the Opus 5.5 rollout. I maintain subscriptions to both providers and use both daily. I can confirm these differences were real, not "it's just vibes and nobody knows anything".

I would bet that 99% of each company's paying customers either did not notice, or did not care enough to consider changing.