I wouldn't go as far as saying infinitely more talented than Roddick. The guy is pretty bad on faster courts for starters. If you call standing 10 meters behind the baseline and whacking the ball infinitely more talented, then that's just your subjective view.
The fact that Thiem may win more doesn't change the fact that he is lucky to win a slam as of now.
Thiem and Roddick are two sides of the same coin.
Roddick won his only Slam title and was merely 13 weeks as #1 in the pre-prime Federer era. As soon as he faced Federer in Slams, his weak nature showed up.
Thiem won his only Slam title without facing Nadovic.
Thiem has defeated Nadovic in Slams (while Roddick never beat Federer in Slams), but you can argue Thiem faced older versions of Nadovic. Still, Thiem defeated a well-playing version of Novak at RG 2019. Djokovic was "only" 31 and had won the last 3 Slams in a row at RG 2019, he was aiming to achieve the NCYGS. Roddick also pushed 27 years old Federer to 5 at Wimbledon 2009.
All things considered, they are pretty much same stuff in different eras.