It depends on the target and the surrounding soil. It’s often easier to pull especially for the random weed that sprouts up around your landscaping. However if you are trying to manage an infestation of invasive species, where the surrounding soil will have a seed bank heavily contaminated with seeds from the years of invasive reproduction, it’s usually a bad idea to merely pull. You can expose soil to sunlight and cause an explosion of dormant seeds. And some nasty invasives are nearly impossible to remove by hand because of their root structure — some species even leave little rhizomes broken off in the soil along the root structure when you pull off the foliage causing a hydra effect.

tl;dr targeted herbicide is a much less evolutionarily selected-for offense, as opposed to hand cultivation which mimics attacks plants have evolved to survive for eons

Dandelions are really, really hard to eradicate by pulling. The roots grow very deep, and if you don't get them completely, the plant can re-grow from what's left.

Even if you do successfully get it out, it really is going to be more work than painting a weed killer on them.

Dandelion roots are ridiculously long!

https://images.wur.nl/digital/collection/coll13/id/676/rec/3