Of course, both the FSF and Debian regard the BSD advertising clause as
an inconvenience, not as grounds for ruling the license to be non-free;
so while RMS's reasoning may be to some degree inconsistent here
(advocating against one inconvenient license and for another),
This isn't inconsistent--consistency does not make sense here. We all
accept various inconveniences to achieve our ends, while rejecting
others as not worth while. And each decision depends on the magnitude
of the costs and benefits. To choose the same option in all such
decisions would be irrational.
The BSD advertising clause produced a large practical inconvenience
because it was cumulative for the entire system. An ad would have to
mention every contributor in the entire system who had used such a
clause, and there might literally not be room in an ad for so many.
I carefully designed the GFDL not to have such a space problem if
there were many publishers, but such a situation probably won't arise
anyway. The GFDL only cumulates for a single manual, not the entire
system distribution. In a nightmare one can imagine large numbers of
cover texts in one manual, but it isn't likely to happen. Where the
BSD advertising clause produced a mountain, the GFDL produces a
molehill.
