It doesn't USUALLY go horribly wrong. It sometimes goes wrong like any position.
Drafting and starting a rookie QB often goes horribly wrong in year 1. Drafting and starting WRs goes wrong more than any position year 1. Neither of these things seem to have been a problem for fans.
The Eagles, a SB contender before the year started drafted a LT to start out the gate. The Texans, another SB hopeful, drafted a RT to start out the gate. The Bills drafted a rookie RT to start and protect thier 2nd year QB.
When the Ravens named Lamar starting QB they also moved Orlando Brown to starting RT. They had no quarms about a rookie protecting thier new starter.
I could go on but nobody else in the NFL seems to have issues drafting and playing rookie tackles.
1. The Eagles drafted Dillard to sit behind Peters. Bad comparison.
2. The Texans were a huge mess on the offensive line. The Cardinals aren't nearly in the dire straits that the Texans were last year today.
3. The Ravens have Stanley, a top 3 left tackle, and Yanda a possible Hall of Famer. You can afford a rookie RT when you have that kind of talent on your OL already. If he sucks you can swing the help to the rightside.
4. Cody Ford wasnt very good last year, but the Bill's line is more talented overall.
What you are missing is that Humphries is easily the best OL the Cardinals have. Teams dont let go of their best OL to start a rookie when they are already talent poor at the position.