perplexity AI vs all?

Hi, I've been looking into AI subscriptions recently and noticed something that doesn't make sense to me financially. Both ChatGPT Plus and Perplexity Pro cost the exact same ($20/month). However, with Perplexity Pro, you aren't locked into just one model. You can literally switch between OpenAI’s GPT-5.6, Anthropic’s Claude Sonnet, Google’s Gemini, and even Grok. On top of that, Perplexity is arguably a much better search and research tool that cites its sources. If you can get ChatGPT's engine plus all the other top-tier models for the same price, why do so many people still stick with ChatGPT Plus? What are the actual, practical differences or limitations of using GPT-4o inside Perplexity versus using it directly on OpenAI's platform? Is it a matter of message limits, advanced features, or just brand loyalty? TL;DR: Perplexity Pro offers GPT-4o, Claude, Gemini, and Grok for $20/month. ChatGPT Plus offers only OpenAI models for the same price. Why do people still buy ChatGPT Plus? What's the catch?