A good software must be backward compatible, which means that the old functions must always work on the new ones. This is what TikZ does since the so-called deprecated operations under 3.0 still work under 3.1 (for example shorten or the intersection of straight lines under 1.18).
Moreover, it is TeX's philosophy to be immtemporal. From this point of view, the numbering of LaTeX software must not comply with this nomenclature