A rogue with 18 dex and Expertise in acrobatics has +8 at level 1. By level 5 they can have +11, making it impossible to fail a DC 10 acrobatics check, even on a 1. Failing on a 20 is easy too, if you are facing a high enough DC. Like a STR 8 character fighting a Nearly Impossible athletics check, without proficiency. Heck, a str 8 can fail a DC 20 check on a roll of 20.
