Then you get someone who uses a tab size of 2 spaces and this allows them for a longer line than you with your 4 or 8 spaces-sized tab. And all alignments are wrong (you know, "indent with tabs, but align with spaces" but then people are not perfect and things end up mix-and-matched) because everything is calculated to fit _their_ tab size and nothing else.
Besides, everything looks horribly indented when looking at the code in Github, which renders huge and ugly 8 spaced-tabs, so lines with just a couple tabs already tend to travel to the right and disappear when using a two-column display :-(
This kind of things are what drove me from using tabs, to preferring and LOVING an already strongly opinionated tool like Prettier.js. Just apply the defaults, no more bikeshedding discussions.