Number was plucked out of my ass. But sure, let’s look at a redwood and see when they start reproducing.
The Sierra Redwood can reproduce sexually (seeds in cones) as early as 24 years old, but one source I found said that seeds are usually not high-quality until the tree is 200+ years old. It also takes about a 2-year maturation period within the cone before being ready for planting. Other types of redwoods can reproduce asexually, which may have an effect on the rate of expression of the mutated genes.
I think Steam NextFests have been a big part of the prevalence of demos. Before we had those, sure, a few games would have demos, but they wouldn’t really gather much attention. NextFests are a good excuse for players to try a bunch of demos (think of the old demo discs that came with gaming magazines) and post about them on social media. This is a great way for smaller games to attract eyes, so now developers are more incentivized to actually produce demos, rather than just neat trailers and screenshots for marketing purposes.