When I think back to when this game was in development, I remember one statement that stood out and I instantly knew I'm gonna love this game. I believe it was Joe who said it:
In order for someone to win and for winning to feel meaningful and fun, there needs to be someone else on the losing side. I believe this statement sums up pretty well why there are so many emotions in this discussion. I also think this statement is very true and the reason why SoT is special.
This is like a flashback to old times, where player interactions actually meant something and where losing a fight could mean you losing everything you had in your inventory.
If you wouldn't lose anything and just respawn instantly with all your stuff, interaction would be meaningless. And as much as losing a bunch of loot can be infuriating, winning a fight down the road more than makes up for it. It's a constant give and take. Sometimes you lose and sometimes you win.
However, it is also important to learn from your mistakes. I believe a lot of frustration comes from new players not being open to trying different approaches. A while ago on our way to devils roar, we met a brig anchored at an island. There was Noone on the ship and Noone to be seen on land. We sunk the ship and it turns out that they had loot from what looked like at least three hours of playing on board. We took it and sold it.
They should have taken away from this not to leave their ship this undefended, especially with that amount of loot or selling more often and to keep a lookout for approaching ships.
Now we went on to do our quests which took about 1,5 to 2 hours. On our way back to the outpost, we saw that brig again. And again it was undefended, again we sunk it in peace and killed the crew that were coming from land with treasure in their hands. And again it looked like all of the loot from the time we sunk them last. So they learned nothing from our first encounter and I am sure this was frustrating for them.
On the other hand I have to say that I don't believe you guys who say you find no peace at all and are unable to progress for days. I solo Sloop often and I duo Sloop with my 9 year old daughter who got no other PC experience and we do get to do our quests in peace. Being mindful of my surroundings, checking and tracking other ships positions and simply trying to avoid confrontation is quite possible. Rarely I do get surprised by some ship approaching from a blind spot but honestly I have to admit that in those cases I have been lazy checking my surroundings and in this case we'll played, you deserve the loot.
Yes sometimes you meet that particularly annoying and stubborn player that seems to have no other mission than to annoy you. You meet them in every game and they always try to find a way to ruin your experience. There's nothing you can do about that. Just remain calm, try to sell what you have and switch servers if they're that annoying to continue going about your business.
Summing it up, I believe a lot of complaints come from people having a couple of frustrating experiences, possibly in a row and are greatly exaggerated out of anger, because it is possible to progress in this game and being left alone for the most part. A lot of people are doing just that solo, you just need to learn being careful. But this is also what makes this game tense and fun.