Forum/board software?

Why has this field stagnated so much? All solutions I am finding are pretty old, mostly Php/MySQL and apparently a big security liability. And the one of new iteration like Vanilla forums are on the other hand mostly featureless and with a UX that doesn't particularly incite user activity. What the heck are communities running on these days?

>>1
Software age is like wine, so old isn't a bad thing, apart from that PHP makes things into shit beer.
>Things that let anybody post text files somewhere for others to read.
Not reinvented into exhaustion at all.