@PyroclasticFlow At least SAO's anime adaptation has a better quality. Maybe the story suffers from many problems, but Kawahara launched it in 2002. Since then he rewrote the first ark and his Alicization at least is not bad. Well, except for a cringy 'gaijins on a submarine' part. SAO together with .hack started the VRMMO genre basically. In 2002 it was very 'novel', what Kawahara was writing; knowing this, I can forgive him for using shitty tropes. Alas, SAO's manga adaptation is garbage.
Now, Overlord started in 2010... The internet and bookshops were overflowing with isekai light novels (anti-hero included) by then, just pick any 20 and study them. So why Overlord suffers from such a juvenile problem as shitty pacing? Why the editor has ignored it when LN got published? Was Maruyama a pioneer of his genre? No. Does he even like his own novel? No, more like he got tired of it a long time ago. Maruyama was even blaming the English community for pirating his shit, with a remark that his motivation is gone because of it.
As you can see, there are not much similarities between SAO and Overlord. If you'll ask me to name one, both have excellent illustrators. Sao has Abec (though it isn't its first illustrator) and Overlord has So-bin. Looking at how much fan arts Overlord generated, So-bin is a major contributor (if not the only one) to Overlord's success.