Not necessarily true. In fact given solid state hardware has limited times it can be written to, I'm more inclined to trust hard drives for important, long term back ups.
They're also safer when it comes to recovering data when things go bad.
With solid state there's the risk of corrupt media meaning data is gone for good. With magnetic media there's more you can do should things go bad.
There's also the fact that controllers are limiting speed on the Amiga, so there's little performance to gain.
Ironically, despite this I actually use solid state hardware in my Amiga. I don't trust it like I do a magnetic hard drive though. Had just as many SD/cf cards die on me (and as a result lost everything with no way to recover) as I have "traditional" drives, despite the fact the medium has been in use for a competitively short length of time. I was also able to recover a decent chunk of data from magnetic drives that have died. (Been pretty lucky though that in the 30 or so years I've been using them I've only lost 4 in total. 2 HDDs, 2 ssds).