While trying to improve at basically anything there will be plateaus where improvement stalls for some time. Does that have to be the case though? As far as I understand there's only really two reasons why someone could plateau: strict physical barriers or not knowing what to improve on. The former shouldn't be much of an issue most of the time - rarely will an activity be so one-dimensional you're limited by a single physical trait. As an example I would assume for doing splits your muscles can only adapt so much in a given period of time and progress will not come in a constant linear manner. Aside from cases like that however, surely plateaus are a result of not knowing what needs to be improved, or how to do so, or even just a mental block. These are all addressable by improved strategies, then. So if plateaus are primarily (or exclusively, in activities that aren't very physical) the result of suboptimal strategy and we're capable of learning anything then with "perfect" strategy you could constantly progress in anything straight to the general forefront of people in that activity (edit: even in mostly mental activities there can still be the physical factor of myelination where if the skill demands certain motor skills or other performances within a short period of time there will still be hard limits to how fast someone could pick something up). Literally never having plateaus is probably impossible but it's commonly assumed that we will hit "soft caps" that are the extent of our personal abilities before reaching whatever level. Perhaps even the theoretical statement to the contrary is enough to somewhat change our assumption of our upper limits.