Unfortunately I'm still not convinced. Can you control anything but the smallest sloop solo and fight effectively against other ships? Can you progress well as a solo player, like you can in multiplayer?
I have played tons of solo sloop in SoT. It's very doable. I reached Pirate Legend with about a 50/50 split of sailing solo or sailing with a crew. I have taken down numerous Skeleton Forts, Skeleton Fleets, Ghost Fleets, Forts of Fortune, Forts of the Damned, Vail Forts and other world events as a solo slooper. I have also sunk numerous two person sloops and larger ships as well, or out sailed them and got away, as a sloop is way more maneuverable than a larger ship.
There are tons of videos on YouTube of solo sloopers owning larger ships in battles. There are also tons of videos on YouTube with tips for solo sloopers. There are also several streamers, such as PhuzzyBonds and HitboTC that steam their adventures as a solo slooper on twitch.
Play the Maiden Voyage adventure and it covers all the basics on land and sea to become a competent pirate. Remember though, this is a game about pirates, so you will get sunk and you will loose loot, as it's part of the gameplay loop, but you will also sink other ships and steal their loot. You can also make alliances with other ships sometimes and maybe even get a server alliance going, which is way better than Safer Seas. Just like any game though, the more you play, the easier it gets in SoT.