The point is that Sonnet at medium or even low will be smart enough for most daily tasks. You’re defining “worth using” as if you always need the highest performance possible, which is what these benchmarks measure, but most work doesn’t need it. You’ll pay more to get the same result. Sonnet 4.5 is very popular as a main model currently, this is a free upgrade.

I use Haiku a lot for agent workflows, if I can get better output at similar prices, Sonnet 5 will replace it completely.