I used the BNB network and was generally satisfied. I used the Huobi network for a few testnets. I bought Kucoin but did not use its network. I did not buy Okex and did not use its network. No doubt these networks will be synonymous with CEXs and will be as successful as CEXs have been. In the next bull, BNB will again try to develop its own network and I think it will have some success, but I don't think the same for the other networks. Exchanges have launched their own networks because the future is in decentralized systems, but we also need centralized exchanges. I think they panicked a little bit unnecessarily.
Yeah, I usually agree that CEX's native tokens have a bright future like BNB, HT, GT, KCS..., but not with blockchain, and blockchains like Heco, OKchain, KCC are the clearest proof.
Perhaps the BNB chain is just a special case since it is backed by Binance. Base could also be the next special case because it is supported by Coinbase - a crypto giant in the United States.
I assume that before any exchange that is backed by another blockchain will decide to develop their own blockchain network, they must have seen a huge success or growth in the current services that they offer. Binance exchange has really become a large exchange in some countries but things could also change in the future and before you know it, another exchange could just emerge and also become very successful.
OKX has grown very quickly over the past year after they announced proof of reserves and conducted very effective marketing, OKX's market share increased from 5.1% to 8.9% in 2023
[1]. However, I am not sure that the development of OKX will create success for OKchain. I had never used OKchain, and I cannot predict its potential.
Ah I see, but why did Coinbase choose Layer-2 Ethereum?
Why doesn't Coinbase create its own blockchain to be more confident.
So that's it, Coinbase has millions of users who trade on the market every day, but why did Coinbase create Layer-2 of Ethereum?
Do you have a detailed explanation regarding CEX Coinbase why not create its own blockchain?
If you have such information, please explain it to me. 
I'm not Coinbase so I don't know what their real purpose is, I will present my subjective opinion:
Ethereum is the ecosystem with the largest liquidity and most users, and Layer-2 on Etherum is the trend thanks to its cheap fees and taking advantage of the Ethereum blockchain security.
Coinbase can target capital (liquidity) and dev/user community on Etehreum, choosing to develop Layer-2 based on OPstack is completely wise.
[1]
Market Share of Centralized Crypto Exchanges, by Trading Volume