As a middle aged IT person that's contractually in high demand with a large number of companies, I interact regularly with older IT personnel (my age or slightly older) and many companies that have turfed many of their IT staff in general.
With the former I often encounter a lack of knowledge on new topics, older people that have grown too comfortable with their idea of 'current' technology without expanding their knowledge while a young guy will come in and say, "oh you guys need this and this and this to solve this problem!" The young guy might be overzealous and his idea might crash and burn, yet he was willing to provide solutions where plenty of older IT people come off as either too unwilling to explore alternative solutions or simply lacking the knowledge to solve difficult problems.
It's also important to keep in mind that as many companies move their services "to the cloud", I've seen a decreased demand for local IT and as this happens I've seen plenty of IT people blame "executive bonuses" or "replaced with young people" when the truth of the matter is that there's less demand for their skillset.
... and quite frankly, there's far too many IT people in the industry that skirt by with limited ability because they're surrounded by other people with limited abilities, so when some new people come along that actually know a thing or two, they can bring to management's attention that their IT departments are lacking in skill.