In olden days the mainsheet ran to the transom and when tacking (in a dinghy) you faced the stern as you crossed the boat, swapping hands for the sheet and tiller on the way. The Laser and Wayfarer are (supposedly) One Design boats dating from those days. Then people realised that with a central sheet you could have less rope to pull in and you could face forward as you tacked making close manoeuvres around a racing mark easier. You have to do a bit of slight of hand behind your back but one soon gets used to that! So boats taking their design pedigree from racing tend to have a central mainsheet. However it limits the cockpit space so cruising boats tend to stick with an aft mainsheet.
I'm sure everyone will tell me I'm wrong!
Peter