How many brokers for classic assets are out there? Thousands, why? Well, just like everything else, why are there a ton of different websites to buy the same things? To sell the same things? etc etc. That's how it works, ultimately the ones who are serious about it will try to offers something better, whether it's regulations, better fees, faster platform, more detailed charts, more trading options, margin trading, etc etc. We do in fact need more cryptocurrency exchanges, hopefully decentralized ones as well.
Thats why every exchange site has its advantages, as you said that they are competing to provide and offer the best facilities for their customers, and of course the most useful and best innovation, will be used by many customers. Exchange sites that don't have much innovation will certainly be abandoned. thats how it works
why many new exchange sites? because they think they can offer the latest technology, better than the previous exchange, that's what they offer to attrach people.