Models of providing computing access in a university department
Suppose that you are a university department, such as the Department of Computer Science. You need to provide access to computing services (and perhaps computing services themselves) to your members, especially to graduate students. Or to put it pragmatically, when a new graduate student shows up how do they get on your network and get access to whatever general services you offer?
(These days the question to ask is 'where do they get whatever machine they use to connect to the network?')
There's at least three ways that we (as a department) could provide computing access to people: it could be provided by the department as a whole, by the professor or research group that people are associated with, or by the individual person themselves. In the old days when computing access was expensive, it was basically always provided by the department or by research groups (in the form of labs, terminals in graduate student space, and so on). These days computing access is cheap enough that in theory you could require new graduate students to buy their own machine in the same way that they have to buy their own textbooks.
(For undergraduate computing the choices get reduced to the department providing computer labs or undergrads being forced to buy their own machines.)
All of these approaches have problems. With departmentally provided computers, the problem is cost and thus the quality of machines that people will get; unless you are very well endowed, you can't afford to buy everyone nice machines and keep them up to date. With group provided computers, the problem is inequality; different research groups may have vastly different funding levels and so their graduate students (and professors) will get machines of quite different quality levels. With personally provided computers, the problem is the cost to the graduate students and what happens if the machine breaks (or is stolen).
(It's generally considered bad form to force graduate students to leave because they can't afford to replace their laptop and so can't get back on your network to do their work. If nothing else, good professors aren't going to let it happen to good graduate students.)
Of course the models are not pure and have never really been. Grant funding has always meant that professors and research groups sometimes bought (or were given) their own computing, even if the department provided some basic level of computing support. And these days a certain amount of new graduate students (and professors) will show up with their own computers which they are quite attached to and are not interested in replacing, thanks.
(One of the differences between the corporate world and academia is that in academia you are not in any real position to tell new people that they can't bring in their own personal computers and put them on your network. Among other things, it theoretically saves a bunch of money and universities can be all about saving money.)
By the way, I don't think there's a single correct answer to this general issue. Every department in every university is probably going to evolve its own scheme that suits the local culture, funding levels and sources, and politics. We (the Department of Computer Science) have our own (current) answers, which this entry has grown far too long to contain.
Sidebar: computing access versus core computing services
I'm drawing a distinction here between access to the department's computing services and the core computing services themselves (if any). Core computing services are shared by everyone in the department and can generally be sensibly used even by groups who have their own computing as well. Computing access is generally one machine per person; if your professor provides you with a nice laptop, you have no use for the clapped out desktop that the department may have planted on your assigned desk.
What this means is that it's much easier for the department to provide a useful backstop of basic computing services than it is for the department to provide a sensible backstop of computing access, because the computing access can easily go completely unused (which leaves the department buying a lot of basic desktops that no one actually wants).