Of course the little L298 ICs blew up when they were seriously overloaded.
Isn't the maximum current one of the FIRST things looked at when designing a circuit??
Yeah, pretty much. The part was right on the red line. So not entirely OP's fault.
I assume the OP was simply on a hunt for "the part that does what he wants", found the IC in question, then come to find out they just barely won't work. There are hidden currents and gotchas to account for that can at times make power parts become a bait and switch. I think that is what he forgot to analyze on this particular occasion and it has cost him.
For the power levels of the OP's motors, the IC's in question are borderline functional at best. It could have possibly been made to work, but at either crippled power or reliability. He looks to have taken his chances with the latter choice and lost the bet.
Bottom line when it comes to power electronics, underestimate! underestimate! underestimate!