Here’s the thing. We actually have NO idea what to look for. Our sample size of “planets that have life” is exactly one, which doesn’t really tell us much. Since we know that an Earth-like planet can support life, it makes sense to start our search there, but there’s no reason to believe that extraterrestrial life might not be completely and utterly different from anything on our little rock.

That being said, liquid water is extremely conducive to complex chemical reactions, which are probably required for complex life. But you also need chemicals that are both reactive enough to do things, but can be stable enough to not randomly break apart. This is one of the reasons carbon is so good at being alive, it’s reactive enough to bond with a lot of other elements (including itself), but not too reactive to be useful.

So basically, this isn’t new. It’s just pointing out that a pure “water world” might not be very useful without a bunch of lively chemicals to boot.

Food can be grown or hydrated. We need minerals for nutrition.

Doesn’t even need water…

A fluid medium helps, but it never had to be water. Whatever the medium is, any life that evolves would adapt to it.