As someone who's done said border run over 40 times, you're basically looking at 2-3 days lost work due to fatigue from the bus trip, along with the cost.
So for someone who is actually working online in Samui, extending at immigration is both easier and much cheaper.
going out and coming back is a fine solution if you live in Phuket or near BKK. If you live in Samui/KPG going out and coming back either takes a whole day or costs you 20,000 baht.
So if someone does actually have all their paperwork and can present it at immigration, that's simply going to be a better option than traveling. Don't assume everyone is in BKK and/or has access to cheap flights.