It's just one of those spots where there aren't enough top end guys, so once you get past a certain point there is a lot of sameness.
Here is the list of guys who got at least 400 PA at 1B and posted a wRC+ over 110 in the process...
Freeman (730 PA | 162 wRC+), Lowe (724 PA | 114 wRC+), Olson (720 PA | 160 wRC+), Walker (642 PA | 120 wRC+), Alonso (618 PA | 124 wRC+), Goldy (599 PA | 122 wRC+), Vlad (525 PA | 115 wRC+), Yandy (521 PA | 163 wRC+), Casas (482 PA | 126 wRC+), Noda (460 PA | 129 wRC+) and Wade Jr. (437 PA | 121 wRC+). Eleven guys.
DH was even more barren with only six met the 400 PA | 110 wRC+ bench marks...Ozuna (582 PA | 143 wRC+), Ohtani (528 PA | 173 wRC+), JDM (472 PA | 136 wRC+), Soler (443 PA | 121 wRC+), Cutch (434 PA | 112 wRC+) and Turner (424 PA | 116 wRC+).
That's essentially 17 good options for sixty 1B/DH spots. There just isn't anywhere near enough supply to meet the demand.