98% sounds like a lot. If someone wins the lottery 98% of the times they play, they are clearly blessed. Getting a top mark (e.g.: 10/10) on exams 98% of the time will likely lead to an honour diploma.
But a restaurant where clients don’t get of food poisoning 98% of time is getting people sick on a monthly (or even weekly) basis. If an employer pays their employees 98% of the times, I definitely wouldn’t want to work there. If I pay before leaving a restaurant only 98% of the time, I’ll be in trouble.
98% is great for exceptionally good things, like dramatically increasing someone’s quality of life, but very low for basic expectations, like a baby surviving a babysitter taking care of them.
If a website uses fancy new browser features and works for 98% of the population, that means that it won’t work for ~150 million people. If a website makes a change and that works for 98% of their visitors, they’re basically kicking out 2% of their audience. Can you imagine a venue refusing entry to former clients 2% of the time just because they’ve “improved their experience”?
98% of the population might not imply 98% of my audience either: something might work for 98% of the general population out there, but only for 70% of my actual audience.
Just a few months ago the topic of nested CSS came up. Somebody pointed out that it is standard since 2023 and safe to use online. I also checked the exact browser distribution of a client’s website (where I would by happy to trim out the scss pipeline). Over the last year, only ~70% of the visiting browsers supported the new CSS features. Even thought this feature is “widely supported” in a general audience, for my audience, it left out 30% of the visitors.
You probably know one hundred people. Picture two of them staring at a broken screen. The 98% statistic is a lazy shortcut. Truly robust engineering isn’t about what works for most; it’s about gracefully handling the edge cases. If a fancy new feature can’t degrade gracefully, then 98% isn’t “widely supported”. It failed to meet the basic minimum for 2% of the people out there.