Yes, I do not deny people do it. It is just not a definitive reason for/of Gaijin’s, nor do we know if many do or not (numbers, we do guess people will do both)
And since GFRB is least populated (overall, before naval, not low but lowest) and not everyone is a TT monkey it seems a stretch to think these sales dominate others. Of course we all approach it differently, as intended (niche game).
It is a choice to “rush” up trees, and a full time job if you want every nation and branch I agree. 7.0ish I am running on fumes, then they added more nations! Then years ago I find out I must be a bad person for bothering to build up my air capabilities (I was a “spade all” player, and with no premium for years it was I agree a lot of work/play). I did both of course, CAP and CAS, but found more enjoyment as CAP overall.
But to say it is the reason Gaijin made/keep GF as combined, and all the provocative baggage with that, is more a feeling. Again, people do a lot of very different things.
All we do know is Gaijin told us their reason. Combined for ground combat, and naval, and PvE (sort of, in both air and ground) is their thing and producing a mode without it, beyond the original air modes (and in all honestly no one would want to play ground in air, it is not serious), would be against their idea for what “they” want WT to be.
If Gaijin had more confidence in their game we could have had so many more interesting modes and features (think of all the assets and easy control method) but is hamstrung by the real overall money maker… “progress” through grinding (of course how far you take the grind is personal since essentially same game at 1.0 as 12.0, and I always recall the player I bumped into with 6,000+ matches in the captured T-34, and good luck to him, he played what he wanted to in terms of that nasty “grind” (since from his details that was as far as he ever went).
I have a ridiculous number of Premiums, but never higher than where I am at (bar Free Abrams, but I only used it once), mostly tanks, a big chunk with most their free repairs still active. It is hard to know what people really do and Gaijin have those numbers only for themselves.
So I agree in part but am aware of other factors, if that makes sense.