strcat Nice to see this is a thing.
I also looked into existing forum software for a (now defunct) project a number of years ago and did not come back impressed with the existing options. phpBB for instance likes to use a "databse abstraction layer" which is mainly just syntactic sugar around the legacy mysql/mysqli modules and if I remember correctly it involved SQL queries constructed using an aggressive amount of string interpolation and escaping. In theory it is possible using this to produce queries involving user input that isn't liable to injection but the list of caveats and when can go wrong when certain things are forgotten would be post in itself.
I am a bit ambivalent of having forums designed around having all the threads on a single page as opposed to the legacy format of a listing of categories and having lists of threads under each category. I suppose if its really wanted one could design a similar layout for Flarum.