"2.0" is a phrase that comes out of software version numbering, but has lost its original significance. The "." in "2.0" used to mean that there would be incremental versions, with major revisions, minor revisions and software patches being in numbers after the dot, so that a program might be called, for example, 3.2.5.3
At some point, well over a decade ago, this nomenclature was borrowed and hollowed out to just using "point oh" after the number two. And "2.0" is extraneous, because when it is used with something like "Web 2.0", there isn't going to be a "Web 2.5", it is synonymous with saying "Web Two", with the "point oh" just being a meaningless techy sounding thing.
Brevity Quest 2021