The real killer of NLEs[0] is variable framerate. Long GOPs just give you higher playhead latencies, but it's still possible[1] for the NLE to actually edit video in such a state. Your computer has to be fast enough or it'll be miserable, but in contrast, variable framerate footage will immediately cause audio desync.

Of course, this distinction is moot, since I've yet to see a (consumer) video source that provides fixed framerate footage. If anyone wants to explain why, I'm all ears. As a result, I habitually re-encode everything before taking it into a video editor as a precaution, and once you're doing that then capping the GOP length is a no-brainer.

[0] Non-linear editor. If you're wondering what a linear editor is, please watch https://www.youtube.com/watch?v=AEMdmnNbCZA

[1] It's actually possible to do lossless editing at GOP boundaries, though I don't know if any NLEs would try doing this.

For linear editing, it could also be this:

https://www.youtube.com/watch?v=_cnQv8JCsX4

It's how I got started, indeed by watching this programme when it was on telly.

Shouldn't will only ever be enforced when it can't be. There's a lot of editing that doesn't require a lot of reverse playback which is where long-GOP really falls down to the point it is worth the slight pain in session vs length of delaying session starting for I-frame transcoding