I added "almost" since I know that it is not really locked behind mp. It just that my enjoyment of the game is dampened when the fights go on too long.
I do find the fights more fun when they are hard. I did all my favourite fights solo on 6star but the less enjoyable fights I do not think I would like to do solo since they take so long.
True, I guess the harder the fights the more fun MP becomes. If they are too easy nobody needs to care about teamplay.
The only fights I've really struggled to solo are the 7* 3x hyper monster quests- I was always running out of time on the final creature, even when prepared and kitted out purely for offensive power vs the marks. I can take down Aleatron, Ukanlos etc all solo, but those multiple 3x hyper quests are just a bit tough for me, particularly with the time wasted waiting for them to appear.
Agree that time investment makes solo play feel a little too long sometimes- the ideal setup for me is two hunters for the tougher quests. Any more than that and the creature just ends up stun-locked and mounted all the time, with so much healing flying around that a team of competent hunters has to struggle to lose. The flip side of online is that weaker hunters can cause a quest to fail by carting repeatedly, but for the most part teams of four wipe the floor with all but the strongest opposition.
I would like to see a mild concession for hunters taking on hub quests solo though, maybe a mild reduction in enemy health. If you can survive for long enough against a creature to take down 80% of its health (or kill 2/3 monsters and injure the third) without carting three times, the last 20% isn't any more difficult, it's just added repetition and dragging the quest out towards (or over) the half-hour mark. Players playing exclusively online with full teams gain resources and armour pieces at a rate of knots compared to hunters taking on hub quests alone, that then take three times as long, and without the backup of extra targets, extra traps, extra healing etc. I wouldn't want them to make the actual combat any less difficult for single player, just a tiny bit less of a lengthy slog considering how much faster and easier tackling the same quest in multiplayer is.