Thing is if like all of their silicon can hit ftw3 clocks it only makes sense to produce those first. Not just from a profit standpoint, but from a waste standpoint. It would be a huge waste to build lower end cards if all the silicon they are getting from Nvidia is coming in at high quality. Especially with the GPU demand right now.
If we assume most are hitting 1800 then they may only be producing 1 lower end per 4, 5 or maybe even 20 high end cards.
Evga can't guarantee they'll get 1800 clocking silicon forever so they have to put it in the high end cards or next year they might not be able to produce the high end ones.
Maybe they'll add another sku between the two eventually if they are finding it hard to produce the lower end ones.