Background to his desire for open (non locked down) systems (covers the period when the MIT AI lab went from the completely open in-house developed ITS to a proprietary Digital system):

https://www.gnu.org/philosophy/stallman-kth.en.html

"...But that machine wasn't designed also to support the phenomenon called “tourism.” Now “tourism” is a very old tradition at the AI lab, that went along with our other forms of anarchy, and that was that we'd let outsiders come and use the machine. Now in the days where anybody could walk up to the machine and log in as anything he pleased this was automatic: if you came and visited, you could log in and you could work. Later on we formalized this a little bit, as an accepted tradition specially when the Arpanet began and people started connecting to our machines from all over the country. Now what we'd hope for was that these people would actually learn to program and they would start changing the operating system. If you say this to the system manager anywhere else he'd be horrified. If you'd suggest that any outsider might use the machine, he'll say “But what if he starts changing our system programs?” But for us, when an outsider started to change the system programs, that meant he was showing a real interest in becoming a contributing member of the community. We would always encourage them to do this..."