Classic big workstations are way more capable than people think - but at the same time it's hard to justify buying one machine per user unless your department is swimming in money. Also, academic budgets tend to come in fixed chunks, and university IT departments may not have your particular group as a priority - so often it's just better to invest once in a standalone server tower that you can set up to do exactly what you need it to than try to get IT to support your needs or the accounting department to pay recurring AWS bills.