FLStudio can potentially do almost anything, there hasn't been a time where I had an idea or a concept and couldn't recreate it in FL.
It does however have a very bad name and it does look very...fruity?
Also about the professional musicians, ask them how many of them started out with FLStudio and learned A LOT from it.
The drum sequenzer may be the most intuitive one to use and create good drumloops.
Still it does lack a good sound library,some features,the quantizing can sometimes be a bit problematic and the buildin plugins (EQ.Compression etc.)
aren't on par with the big (expensive) boys.
I haven't really used another DAW, besides playing around with Reaper at a firends house,but I did get the impression that the Sound was different.
And it's not like nobody uses FLStudio at a professional Level,9th Wonder has used it (still uses it?) and it's more suited towards the electronic music producers anyway.