Isn't that a pretty lame excuse? In exchange for saving a few dollars, you're going to hand over the keys to your entire account -- or possibly your entire net worth -- to an unknown, unregulated, unaccountable corporation?
It's not an excuse, just an economic reality. People prescribe value to things. The value of a typical transaction at a centralized exchange isn't worth the on-chain transaction cost. That's a problem with current blockchains, not a problem with the purchaser.
I can send thousands of dollars (with a 'priority' fee schedule) for less than a dollar in fees over the plain 'ol regular BTC network. It may be an economic reality, but it's a negligible one.