You assume that everyone in the company is acting rationally, and that everyone has the same goals and values. This is usually not the case.

The truth is that for most types of applications, there are several technology stacks that would be perfectly adequate. You get into the tradeoffs, and unless the benefit posed by a specific thing is immediately obvious, these are a matter of subjective judgment. Great technical minds will have differing subjective judgment; no one's judgment is exactly same as another's.

People also usually do not understand their own motives. This is the origin of fads. Everyone suddenly agrees that THING_Y is the best, and then, the next year, everyone suddenly believes it's THING_Z now. If someone can present a dense, semi-passable argument in favor of it, the rest of the uptake comes down to marketing. This is true no matter how smart you think you are.

If you have a technician who prides themselves on always knowing about new technologies, and that's their reputation, it's likely their primary motivating factor will be continuing to propagate that self-image. They might not even realize it.

They will come and say "There is a new tech called TECH_X and it allows us to do these amazing new things!" As long as TECH_X has some value proposition and isn't a blatant or obvious bad fit (meaning obvious and blatant to everyone), their argument is plausible enough and they'll run with that.

They think they're doing this because they learn all the new things and it gives them a competitive edge. In reality, it's because they view themselves as cutting edge, they want everyone else to view them as cutting edge, and need to feed themselves and everyone else some proof validating that desirable conception.

The difference between "political schemers" and your average employee generally comes down to their naivety around the universality and importance of these functions. Which is another danger -- the less-naive employees in the ranks will be actively working their own angles here to attempt to manipulate the psychology of the people around them. This can and does invade technical choices. You can make the best arguments in the world for your stack, but if you have a political competitor, they will work to undermine you, often in non-obvious ways. If they feel now is the time to strike and they can embarrass you, they'll do so; if not, they'll agree and subtly work to sabotage your plan.

There's another type of employee here; the type who wants to keep his day job on cruise control, and will oppose anything new because it would make his short-term daily existence more difficult (and perhaps long-term if the improvement could reduce inefficiencies so much that he becomes redundant), regardless of organizational benefit.

There are many arguments to be made in favor of keeping the status quo, so he will look OK; if your new stack is a wild success, he will be able to say "Oh, I just needed some time to come around" and if your new stack is an abject failure (which happens much more often than people wish to admit, and even more often, it's made to appear an abject failure by political competitors regardless), he will be able to say "I told you so".

People are naturally self-interested and will behave that way all that time. Management must look outside of the individual goals of the employee or team and consider what is in the long-term interest of the organization.

tl;dr This is naive; a purely democratic approach doesn't work because people's goals and values don't necessarily align.