[CJefferson]

In some vague sense, any solver for an NP-complete problem, must either backtrack, or keep accumulating information and possibly exhaust memory. In practice every practical solver I know of for NP-complete problems backtracks.

Now, they often do all kinds of other clever things on top (learning, restarts, parallelisation, heuristics), but when the going gets tough, there is a lot of backtracking.