1. 98 % can be “good enough”
“98% is plenty.” — pixl97
2. Business/market calculus
“Profit is often at the margin.” — silvestrov
3. Real‑world technical constraints
“I still have significant traffic at some clients from IE9.” — epolanski
4. Need for graceful degradation / progressive enhancement
“When you add something, are you choosing technology that is widely available and supported, or are you choosing to throw 0.N% of users under the bus for some benefit?” — ryandrake