Yes.
As you could see with BDSP taking 95% from Diamond and Pearl before postgame, which barely adds anything more from it besides Giratina Origin and the Platinum E4 teams during the pre-Stark Mountain rematches.
Were it not for Platinum, Sinnoh would be as panned as X and Y are today, and much like Arceus was for it, Z-A might be the one chance Kalos has, as they didn't get a second chance to recover from mediocrity for over 10 years while it took Sinnoh around 2.
With how basic the campaign is even to this day in the Switch games, hindsight for sister games/alternate difficulties is why many gens are looked back on so fondly. Crystal, Emerald, Platinum, B2W2, and to a lesser extent Yellow, FRLG, HGSS, ORAS, USUM.
The only original games people often go to are RGB because they were the originals, and BW for only having Unovan mons in the campaign and (even if basic PETAshit) the best story/JRPG experience at a base level.
Every other time, you go to the following game or remakes, which is also why the Switch originals like SWSH and SV feel so empty on a playthrough: it's simple by design, and the best you get for replay is paying DLC @50%~ the price of the game for a few extra families in an alternate area like the Isle of Armor or Kitakami, without adding difficulties or adding things in the campaign to reflect this until the VERY END of the final update in rematches where it doesn't matter against your LV100 team.
>TL;DR
Platinum is the strongest example of hindsight of a 'core' entry (first of a generation) followed up by an update/sequel to its main story with extras rather than separate DLC from the experience or being one-and-done, as without it the Sinnoh region wouldn't be considered iconic nearly as much as many do today, and I'd argue it's visible in the Switch games as well, not even adding a possible difficulty option via update post-launch.
