Quality is subjective but marketing is not. Every person has a different taste, I've played some "good" indie games that bored the socks off me. F you have enough people coming through the marketing funnel then only a truly awful game will fail to find admirers.
There are subjective qualities such as visual quality but there are also objective qualities such as "hours played" or other measurable ones.
Also people will do the marketing for you if your game is good but if it is not you will need to convince them (money most likely). And that is what bigger companies often do (via Twitch streamers e.g.) and what indies cannot (especially solo devs).
Quality is subjective, just like beauty or really anything else. But it turns out a lot of people share the same subjective views of a lot of things. A game that would be subjectively appealing to most gamers will generally do much better than a game that does not. A sufficient amount of marketing might be able to offset some of that effect, but not always, and only at great expense.
