Save bloat is more often related to excess values not being properly discarded by the engine, if I remember right. So it’s not that the objects themselves take up a lot of space, but the leftover data gets baked into the save and can end up multiplying if the same scripts/references/functions get called frequently.
It was a lot worse with Skyrim’s original engine, and got better in Fallout 4 and Skyrim SE. The worst bloat happens with heavy modlists, of course, as they’re most likely to have poor data management in some mod.