It's not harder to solo, it's just that anything got the worded "Dated" sucks compared to the new Shiny Stuff. Unless you have full Darkhold gears, you will be much less effective. This is even more apparent for DoW because you rely on Equipment to be effective a lot more than DoM. SE sneakily "wiped" your progression and make you start from scratch in term of gears.

And you can still oneshot stuff around your level, if you know how.