The problem with these sites are that most people use them to read the most readily available series. Like, for those in the US at least, you can get most of Shonen Jumps library for only 2 dollars a month. When something is that cheap there's no reason to read like One Piece on another sites, especially when I tend to find Viz's translations better than the fan-translations (though this can be case by case). Like if you can't afford that, you have bigger things to worry about than reading Boruto or something.
That said, I don't really hold using the sites as some sort of litmus test, especially considering series aren't always available outside of the States & Japan. One of my online friends from Sweden relies on scanlations because a lot of manga just isn't available locally and manga subscription services either don't exist over there or have lesser/different content offered. Beyond that, some series just aren't legally accessible. Let me give two examples . . .
I. The anime Monster, one of my all-time favourite series. I believe you can still buy the manga in Omnibus format, The Perfect Edition, I have a few volumes myself since I love the series but, if you want to watch the anime, which did have an English dub, you can't legally do it. It's not currently available on any streaming platform, and they've only ever released the first 15 episodes (out of 74 btw).
II. GetBackers. This is the last series I've read through scanlations. The series is out of print over here, meaning if you want the physical copies you're buying them used so you're not even supporting the original mangaka anymore. And even if you did manage to collect the entire series, guess what, they never actually localized the full series! The last ten volumes were never released in English, they didn't even finish localizing the story-arc they were on. You could import the full series from Japan maybe, it's a nice gesture but imports raises the price and if you don't read Japanese, you basically wasted money on something that you can't use.
I definitely feel like you should support the official release whenever you can, the main reason I read mostly Shonen series is simply because of how cost effective it is with Shonen Jump's 2 dollar price tag. But I do feel sad that the loss of sites like this will prevent people from experiencing series they may love but have no viable legal way to actually support, and if the main creators aren't making money off it anyway, I don't see any moral issue with people reading series that way.