Seems to me that approach to the DH has been increasingly rare over the past decade. With a few exceptions (like Nelson Cruz) AL teams also use that spot to spread out guys and give their regulars a blow. The primary DH still has to to be able to play somewhere and the Phillies don't have the $ left for a full-time bat (at any position).
The Phillies' problem is not that approach; the Phillies' problem is their 9th-best offensive players who aren't at SS or CF (Bohm or Gregorius), the most likely DH options, aren't good enough. Get rid of Didi's salary and you could sign someone to be a mostly full-time DH; keep Stott or Bohm in AAA and you can sign a bench bat good enough to DH 80 games (but then your 3B bat still stinks, potentially, and so does your SS on both sides of the ball).
I would still try to get a Brad Miller or Tommy Pham over a guy who can play CF. But Soler is probably out of that price range unless teams are looking hard at his entire 2021 (and when you look hard at his entire 2021 he is not necessarily a guy you want to hand the full-time DH job to either).