I think it can help. Traditional DBs generally worked on the assumption that if you were scanning through records one-by-one you'd already lost, so naive ideas

I think it can help. Traditional DBs generally worked on the assumption that if you were scanning through records one-by-one you'd already lost, so naive ideas that you can just write Really Good SIMD won't help. But there are plenty of smart people who understand this well and can write SIMD code for what remains. Scanning non-DBMS stuff can benefit a lot from good SIMD (although writing code that's tremendously clever that allows you to run faster than memory bandwidth permits is also fairly self-limiting; the faster you go, the less likely anything can keep you fed).