Well I mean, tech in other games simply refers to uses of game mechanics that weren't immeditely apparent. In Smash, it tends to need to be a glitch or something more technical, right?
Wel the definition of tech is a little more complicated than that, but I won't go into exacts right now. I'm thinking of making a post on it since it's kind f a confusing and imprecise concept, but that definition works for now I guess.
But what you hink of as smash techs is what most people think of them. But that's actually not exactly correct. Smash does use the same definition of everyone else, they just have that reputation of it being "glitchy" stuff because like I said fist of all the nature of the game includes a really really strange physics engine tht causes a lot of the techs to either look glitchy or actually come from unintentional/glitchy stuff. That's also why a lot of smash tech is so complicated. Simple inputs have been fixed on the engine but more complicated ones lead to unexpected results due to the engine not really knowing how to handle it. SThe second and third reason are kind of related. Sakurai's views that having a big skill gap between players i a bad thing meant that when people discovered things that allowed for a big skill gap, they assumed that those things weren't meant to be in the game and those beliefs turned into popular rumours.
In melee the two" biggies', wavedash and L cancel, were intentionally not fixed and purposely put in respectively. The only game that
actually heavily relied on glitches for tech was brawl, because Sakurai tried to sabotage stuff but could only really do it or some basic things. Also for some reason brawl just had way more glitches. Maybe because it was already behind schedule so they didn't have as much time to bug test. But dacus, bdacus, glide toss, and a bunch of other stuff were all "glitches" so to speak. I think the only at that was in that was supposed to be in for that game was teching, which has been present in all the games. For some reason I really can't fathom Sakurai hasn't changed his opinion to have a problem with teching, even though it's a very similar concept to L cancelling.