What is noticeable is that there is a significant dip in performance if you use mods to allow more sims on the lot and increase the household size, so I suspect this has a bearing on the design decision to go for a single lot. My machine starts to nope out at around 50 sims on the lot, though I have pushed it to 100 controllable sims once - for science :)
There could be possibilities if there was more scope for customising the surrounding neighourhoods. Windenburg Town is particularly woeful in the lack of interactions outside the lots compared to Willow Creek or Oasis springs.