I think some problems are simple enough that they can be dealt with "blindly", but some problems turned out to be tricky in special ways that evolution was more able to solve via consciousness than blind information processing. And from there, we find ourselves, with that new capability in hand, able to repurpose consciousness to newer and newer things. Then retrospectively it can look like consciousness wasn't "needed" for certain problems.

So I think even if you want to make the sense that consciousness solves a lot of problems it doesn't need to, it may have been a "real" solution to a "real" problem at some point in our history. And from that point on, it was no longer important whether it was the best solution.

I do think it's fair to say that lots of remarkably complex informational problems are solved in a p-zombie way, which is to say, with every outward appearance of intelligence (slime molds solving mazes, collective behaviors of ants). So I do think evolution or nature writ large "agrees" with you that consciousness isn't strictly necessary.