Mushoku Tensei existed before most of the "current" wave of Isekai stories and consequently tropes. There were a lot of isekais before it, but those belong to an older generation and had a relatively different set of tropes (i.e. Fushigi Yuugi, El Hazard, 12 Kingdoms, etc.)

The story also has a full conclusion, so it won't suffer too much from random asspulls since the author has had the chance to fix the story from the WN to LN transition. I've only read the first few chapters but hear about this a lot in the LN community.