First a definition for this question, because there are many kinds of sci-fi out there and they sometimes liberally use cool sounding words without explaining them:
A disruptor is a kind of weapon that weakens, or "disrupts", either material bonds (breaking a material into molecules), molecular bonds (breaking a molecule into atoms), or atomic bonds (breaking an atomic nucleus into protons, netrons, and free electrons. Almost like instantly turning into plasma).
Temperature can do these things, but the idea behind a disruptor, specifically, is that it happens through some kind of catalyst, rather than brute-forcing with insane amounts of heat.
Would such a weapon physically be possible (even if we don't know how to make them just yet)?
How would a target realistically behave when hit by a disruptor?
But Steam isn't a walled garden, or a monopoly.
Valve has done nothing that monopolistic corporations have done (i.e. Disney or Nintendo). They have kept themselves relatively small, private, and focused on providing one service really well.
Every other competition has only ever tried approaching what Valve does with Steam with shortcuts and quick money grabs.
It's all fine and dandy to cry and complain about monopolies, but nobody even really tried. Epic's store was, and still is, a laughing stock. That is what Valve is up against.