Perhaps, but the GPL licensing of this code isn't a barrier to them doing that, since most of them will be running web services that can use GPL code freely without having to release the rest of their code. If it was AGPL then maybe you would have a point.
The issue in this case is that image formats need widespread support to take off, and picking a license that is incompatible with 4/5 major browsers ensures that won't ever happen.
