The primary problem is using agile all the time instead of when it is actually intended to be used: short term work that needs to be done quickly by a small team that are all on the same page already.

I think you got it entirely backwards.

The whole point of Agile is being able to avoid the "big design up front" approach that kills so many projects, and instead go through multiple design and implementation rounds to adapt your work to the end goal based on what lessons you're picking up along the way.

The whole point is improving the ability to deliver within long term projects. Hence the need to iterate and to adapt. None of these issues pose a challenge in short term work.

I wonder why anyone would downvote you. to break down what you said:

The primary problem is using agile all the time instead of when it is actually intended to be used

this applies to everything in life. zero reason to downvote this unless you're a zealot who doesn't understand nuance

short term work that needs to be done quickly by a small team that are all on the same page already.

the whole point of agile is to be short term, maybe your downvoter thinks that the team doesn't need to be on the same page???? don't know how that is in any way a good idea. it means you haven't done a good job communicating...

Some parts of it are still helpful as part of a blended process, like more collaboration with the customer and responding to change, but those can easily derail a project if not everyone is on the same page through scope creep or losing sight of long term goals.

anyone that disagrees with this hasn't actually gone through with Agile according to all the tenets. It sucks for anything more than the tiniest projects that don't need long term maintainability. I'm guessing this is where someone disagrees, but I can't fathom why. Maybe they've only worked at one place, they think it actually is working, yet haven't been there long enough to see the downsides or something.

I don't understand what you mean, why would coordinating across a large group be against the agile principles? It sounds like the main issue here is lack of communication and planning which are both important parts of any process including one based on agile.

Planning becomes more important for a larger project but if you hyper focus on sticking to the plan even if things change you can end up delivering something that is not useful for your customers, so I think the principles still make sense there.