I remember using FT ][ under Windows 95 as my friend at school introduced me to it. Some of the more complicated songs were bigger than MP3s of the time (that confused my tiny brain) but were playable on my garbage 486 DX2, unlike MP3s (I was poor and using throw-off computers that others had thrown away).
Well yeah, the samples in the MOD files are uncompressed (or losslessly compressed, no idea), so if you have a lot of different samples, I can imagine you might end up with something bigger than an MP3 file. I guess none of those were modules initially composed on an Amiga though ;)
Happy times.