It’s not at all unreasonable to assume many companies are still running older Microsoft server software. In fact, if you consider in full the total amount of software that enterprise may host as part of workflow, these server OS’s absolutely are maintained.
There are many reasons “hold-over” OS’s like this stay. Consider in manufacturing, where regulatory processes include both names of software and their express function within the flow of a procedure. imagine that procedure is written into quality policies. Guess what, it stays until it’s rewritten. This is how things stay. For the IT department, this becomes yet another case of isolating the whole system and maintaining it in place.
In recent years, we are fortunate enough to now have options such as a hypervisor where we can take old “systems” at least as they exist as hardware, transition them to virtual machines, isolate them, and call it a day, still this is not a complete answer.
Companies in the modern day need to step up IT budgets, seek out, hire or keep on retainer experienced staff to insure a zero day event where these older systems come back to haunt them.