I am not sure about that offensively, I mean Henry almost always comes out on 3rd and long, it's just that we didn't get them in that down Sunday. They didn't even have that many 3rd and shorts.
KC only has 2 players who play all the time and that is who you mentioned, Kelce (the best TE in the game) and Hill (possibly the best lateral quickness/pure speed combo) in football. The both play just less than 90% of snaps. But the rookie RB plays less than half of the snaps, and I am sure that surprises you. The rest of the WR corps play betweeon 1/3 and 2/3 of snaps.
Here is a link if you want to look at snap counts. https://subscribers.footballguys.com/teams/teampage-kan-6.php
It might seem that other teams are different than us in this regard, but they really aren't.
I bet you would be surprised that Henry only takes 65% of the snaps. Brown and Davis average about 80% when healthy.
The league utilizes all kinds of specialized personnel all the time.
All teams pretty much have different personnel groupings that they utilize a lot. Belechik probably started this trend. NE certainly made it's money switching players in and out depending on the situation.
Haeg went to Tampa on a one year 2.3/3.3M contract. IIRC, he was offered more money than here. According to PFF, he's played 93 snaps, hasn't given up a sack and has one penalty, but his PFF score is somehow only 51.1. He's listed as a T everywhere I see but might be playing G.