It’s easy to understand, but not easy to live under. If the worst case is I lose 25% of every “extra” dollar in some range, I have to think about it way less than if I lose the entire benefit for being 1 unit of currency over a limit.

In the former case, I can think/worry about it for 10 minutes per year; in the latter case, if I’m close I have to think/worry about it a lot more and carefully plan out and estimate things like tax-deferred savings and capital gains/dividends/capital gains distributions to make sure I don’t earn an extra dollar and pay $10-25K of marginal tax on that dollar.