- How severe is the impact, and
- How close is the default state to the constraint
Kerb cuts help everyone. Kids, the elderly, disabled people, and anyone distracted by their phone are all less likely to fall on their face and lose a tooth.
Web accessibility helps websites go from unusable for disabled people, to usable.
On the other hand, when a dev puts a website on a diet it might make it load in 50ms instead of 200ms for 99.9% of users, and load in 2 seconds instead of 2 minutes for 0.1%.
So it doesn’t impact anyone meaningfully for the site to be heavy. And for that edge case 0.1%, they’ll either leave, or stick around waiting and stab that reload button for as long as it takes to get the info they need.
As shameful as it is, web perf work has almost zero payoff except at the limit. Anyone sensible therefore has far more to gain by investing in more content or more functionality.