AI has been a field within computer science since at least the 1950s. It encompasses algorithms for making decisions, which is why so many technologies are labeled this way. “Intelligence” may seem like an odd choice of terminology (some people conflate it with sentience or similar), but general machine intelligence is one goal of this study, and the applications of AI are putative steps to that end.

Back when those guys started talking about what methods could get us there, things like decision trees, symbolic manipulation, neural nets, were all potential pathways that were on the table. So these get included in the field because that’s where and to what end they were produced.

Another thing is that intelligence can be narrow in its domain. A character in a video game that needs to move from point A to point B can do so following something like the A* pathfinding algorithm. In the domain of graph traversal/pathfinding, it’s hard to imagine something much more intelligent (or fit to solve the problem) than A* despite being a simple algorithm.

But yeah, as a marketing term it is kind of silly since most people don’t know what it means. It remains a useful categorization for a broad field of study/research in CS though.