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?