Well, it "made" sense for intel because this allowed Altera to switch to Intel fabs. Not saying it's a huge strategic value or anything, just saying that's the difference.
Altera switched to Intel fabs from TSMC in 2013, so yeah it makes sense for Intel to pick up the folks you don't have to do much to integrate into your manufacturing process. But AMD and Xilinx both already being fabless meant it was a wash...no process integration to be done.
Xilinx was fabless before the acquisition. I'm missing how that made less sense.
with all the zero interest rate money floating around
Hehe...as one of my finance-world pals said: "everyone's doing M&As like drunken sailors".