Can't speak for many others, but Trickster Online definitely had a significant difficulty curve, and even being the "proper level", soloing areas became near impossible past around level 100 unless you were extremely overleveled/overgeared, bosses evenmoreso. Aside from the grinding necessary on the occasions when quests ran out and the occasional difficulty in finding a party at higher levels, I found the difficulty curve pretty okay.
The game was designed sort of weirdly, starting with wide gaps in leveled content with "medium" level areas added between the dead space between other areas later, so grinding was unfortunately a necessity parts which is initially why I quit the game. International servers shut down last year though.