Solved Just wondering about locked threads

I see in the Do It Yourself (Not Computer - Related) forum that it looks like all is locked from the end of March, and all previously posted. There's that lock symbol....
Is this just policicy due to a certain time limit due to inactivity on threads?

I certainly see why some threads are locked/closed for various behavior such as vicious trolling, spamming, and the like. I don't see any of that going on in that particular forum...
And you'd think by now I'd know the answer to my own question here
So maybe it's a stupid question, but those are easily answered, so I'm told

 

It's what I thought most likely, thanks Derek!