100%. pokemon has plenty of true randomness (hax) built into the game, but after playing SV for a month (sitting at 1700 rn), I'm realizing tera is not an example of randomness at all. unpredictability, yes, but not randomness.
every decision involving tera, from selecting what type in the builder, to knowing when to pop it during a game, to reading when your opponent is gonna use theirs, is about making informed decisions based on what you understand about the meta. you can't lose a game due to an unexpected tera in the way you can lose to an unexpected crit - the factors are solely in the players' control.
there are/will be mons who abuse the mechanic too much and should get banned, but tera itself is not random or uncompetitive.