Imagine if an experienced pilot crashed on every 20th landing.

Part of the excellent case why you shouldn’t roll for the routine. Take “town downtime activities”.

If a character is a lifetime street urchin, they should be able to find a few “safe marks” versus rolling to snag some risky but lucrative pickpockets. A talented musician doesn’t flub every 20th note, but you can certainly reward bigger rolls with bigger tips.

It's more that it's just more work for the DM in this case. Every time a skill check is called or considered, the DM has to reconsider if the character considers this a routine or trivial task. You can see this in the stats: if the character's modifier is 5 or less than the DC, it's trivial. But you also must consider even without a high mod vs DC, is this a task the character has performed hundreds of times before? I try not to come up with solutions, or utilize WOTC solutions that make a lot more work for the DM. Especially if there's already a rule or slight tweak that makes sense and prevents this work: in this case, no crits for skill checks.