I had someone bitching at me this morning because I was watching Garuda intro. It's an amazing intro I watch everytime and it's only 1min but nope, he was complete freaking out.
Bitching at you for that is probably unreasonable but if you're curious as to why that happened:
When Garuda HM is having a bonus window, she's by a wide margin the most time-efficient fight for light farming. A good group can kill her in about 2 minutes flat. A great group can do it in slightly less.
Given those timeframes and the fact that a window lasts for 2 hours exactly, people want to maximize the amount of light they can get from her while she's in bonus. So a 1 minute cutscene is 50% of another Garuda that they now can't do because of you. I'm not saying they were right to yell at you for it, but I promise you that's the reason they did.
Short answer- to not have mechanics enforce any progression limitations on the people who wish to go faster.
It is a player driven function. An agreement between players, if need be. If people wish to stop and smell the roses, make your request known (either via PF or at the beginning), and follow what the majority of the party wants. If you are in the minority, you just deal, or leave. Enforcing this with mechanics would be far worse for the future of the game.
If anything it effectively challenges what you've been saying.
Cutting 33% of the time means you can achieve the same number tasks in 40 minutes rather than 1 hour. For a simple example, it means the difference between 112 lights instead of 160 over the span of one Garuda window.
It adds up with every.single.delay.
All of them do end up there. They are just in different spots.
But side note. I never watched cutscenes because I was told that I needed to in Castrum and Prae. Going back to the inn was an inconvenience. So when I went with an FC mate to prae for the first time I turned cutscenes back on. The dungeon actually makes sense now. Before it was just oh hey Ultima... Hey Ultima again... Where did lahabrea come from.
It is a matter of efficiency. Be grateful that the loot/tome-to-time ratio is sufficient for the other people to be willing to help one person through the dungeon or trial, rather than seeking something more efficient, and leaving the aforementioned player to fend for themselves.