Your information about Amiga isn't correct. In Europe Amiga had really vital Amiga BBS scene. ANSI "BBS" art as a product of IBM-PC world is only true, if you're talking about this so-called "block ascii" that was made using PC's CP437 character set. On Amiga there was a huge amount of artists doing "line ascii" based ansi art for boards (ISO-8859-1).
For example in 1995 in Sweden there were still loads of Amiga boards: http://www.textfiles.com/bbs/BBSLISTS/elite01.txt
This is the list of boards the list maintainer considered worthy to be listed.