If that is the reason then it is purely a mistake on DEX not on Ethereum because it is the DEX exchange party that sets the expensive transaction fee, not the Ethereum party, because currently the Gwei transaction fees on the Ethereum platform are very low, only 18 Gwei, so the reason is that You say that is a very ridiculous excuse and BNB will not be able to take over ETH under any circumstances.
there is always a possibility and I believe in it, because in crypto nothing impossible will happen. but the problem is that many are not just limited to the high costs that occur in ethereum, but can include other things, that's why I say nothing is impossible in crypto and it can happen.
if you look at what you said it could be true and ethereum should also be able to take action because it involves him too if he doesn't cause high costs, but why this seems to be silenced and finally many new projects are looking for other alternatives. many have tried in various ways, including one with the BSC, although other measures can also be taken.
the sad thing is that it can't send the bounty results to those who deserve it because the costs are very high, pityy for those affected by that