This might be the case but I don't think that is the main reason. In fact, Europe has many excellent universities. I believe one of the reasons that Europe is lacking IT giants is because investors are risk averse and they would rather invest in tangible industries. For example, in Switzerland which is ranked first in global innovation index [1] the IT industry is almost non-existing even though it has vibrant medical, food, financial industries.
Another reason in my opinion is the lack (or weakness) of military industrial complex. In the US many innovations are funded directly or indirectly with public money through military contractors and projects. (DARPA, Silicon Valley [2], Internet,...). Just by looking at patent portfolio of NSA you get a taste of technology transfer with public money to private sector.
1- https://en.wikipedia.org/wiki/Global_Innovation_Index
2- https://www.youtube.com/watch?v=ZTC_RxWN_xo