There are actually a lot of other problems besides non-free graphics and
wireless dependencies. HP, Lenovo/IBM, Toshiba, Sony, Apple, and Dell all use
digital restrictions for example. This does happen to mostly impact wireless,
but is a distinctly separate issue. What it means is that you can't buy a
laptop from one of these companies an expect to be able to replace the wifi
card in it with one that is compatible with free software.
I highly encourage people to boycott these companies. It goes beyond
incompetence or not caring. They are actively working against the user.
There are lots of other issues that can impact support that have less to do
with proprietary software and more to do with design. For instance
software-based switches for turning on/off wifi cards (ie you may have a card
that works, but if it's always off, and you can't turn it back on, then the
laptop won't work terribly well with GNU/Linux), support for special function
keys (adjusting volume/screen brightness), and power management.
This is a short list of problems people frequently experience. There are some
other older issues that have purportedly cropped up again too relating to DRM
that I had thought were permanently solved. However I haven't had time to
confirm the claims or look into solving the problem so I'll refrain from
going into it. It won't impact most people in either event.
You may also run into issues related to restricted boot, but I can't really
speak too much about it. I'm not sure how common of a problem it is with
off-the-shelf x86 hardware in the worst case situation. At its worst you can
brick systems and/or simply not be able to install GNU/Linux. I believe it
would also include lesser problems with x86 that simply make loading
GNU/Linux more difficult.
There are also issues with CPUs related to digital restrictions. While it
won't work in Trisquel or any free system today anyway the more systems that
ship with the technology in the CPU the easier it becomes for sites to use /
arguments to be made for adopting/requiring it. Today you can watch most
content on YouTube, but tomorrow that may not be possible if Google
implements code that utilizes this technology in the CPU. Avoid Intel CPUs
with 'Trusted Computing Technology'. I'm unsure what AMD calls this
technology, but a version of it is also present in modern AMD CPUs.
