The previous games were all on the Nintendo 3DS, which has a larger install base because the 3DS came at a variety of price points and was therefore more accessible, and the games were also cheaper. To compare, there are only maybe about 20 million Switch units sold (last estimate was about 19.6 million back in June), and LGPE comes at two different price points across four UPCs (two being the regular games, two being the ball bundle). To even compare the numbers is intellectually dishonest.
Coupled with preorder culture starting to die off thanks to a string of disappointing AAA releases, and Nintendo pushing Smash Bros. much harder with their Directs while LGPE just gets a few trailers and screenshots, of course it's not performing as well as it could be.
But nah, /vp/ is just going to post Screaming Kanto Man over again, or an unflattering closeup of Masuda's face, or call all Pokemon GO players retards, or some other dumb shit.