Just because there are other games like Hellblade, so much so that a genre exists, does not mean that it's not a niche title. Yes, there are other games that are walking simulators. And those games, while popular with a minority of gamers, often reach a level of critical acclaim. But in the medium as it exists today, walking simulators are a niche genre.
What Remains of Edith Finch is a walking sim that is fairly high rated on
Metacritic - higher than HB2 in fact. WROEF was
Eurogamers #2 game in 2017 (Hellblade 1 was #9 that year), was in
Game Radar's top 5 games that year at #5, and won best narrative at
The Game Awards. It's regarded as one of the best games in the genre. To my knowledge WROEF never charted on any top sales charts. It wasn't in the best selling games of April or May 2017 (it released in April). It certainly never entered any any year end sales lists. Yet it's considered a success in the genre, because the genre is a niche genre, full of niche games. WROEF also had a max Steam
concurrent player number of 564 players, Hellblade 2 peaked at
3982, with a 24 hour peak higher than WROEF's lifetime. People are looking at HB2's steam numbers and declaring it a failure or disappointment, but it's numbers are well above on of the best games in the genre - A game that beat the original Hellblade in many best of lists the year they both released.