The vast majority of bikes sold are not gravel or CX bikes though. Nearly all otp cheaper bikes come with some form of Shimano, I reckon the portion of their business for selling individual groupsets is much less than OEM to manufacturers, let alone one niche section of cycling
Surely groupset specs drive sales to an extent. Anecdotal I know, but the number of CDFs/do-it-all bikes you see about I figure it must be worth the small amount of R&D, if only to retain market dominance at all levels.
Literally all they'd have to do is design a derailleur that clears an MTB cassette with road cable pull. (And maybe a clutch mech version for 1x.) The R&D is minimal. There's got to be some very significant reason that they don't want to do it.
The vast majority of bikes sold are not gravel or CX bikes though. Nearly all otp cheaper bikes come with some form of Shimano, I reckon the portion of their business for selling individual groupsets is much less than OEM to manufacturers, let alone one niche section of cycling