Ben Simmons, Giannis, Kawai, Harden, Durant, Lebron, etc are all players who are taller, don't technically play PG, but do allot of the ball handling for their team and would match up well for Carsen. This is just a quick list off the top of my head.
Also, coaches like Pop, Rivers and Brad Stephens have been very good in the past using shorter scorers very effectively while being able to hide their weaknesses their height brings.
Probably on of the reasons Boston is often picking Carsen in the Mock Draft because Brad has shown the ability to get the most out of a player like Carsen.
On a side note, if CMP can take a player like Carsen, 90th or so ranked in his class out of college, and turn him into a 1st round pick in 3 years, I just don't understand why more players don't want to play for CMP. I will say it again, anyone ranked 50-100 should want to come here. I get the Zions of the world want exposure and thus a Duke, Kansas or Kentucky, but guys in the 50-100 range should be lining up to come to Purdue.