there was a mix of this in some of the ufo sequel games. you research x and the game becomes harder aliens start using new tech. but there was also a time limit flag where the aliens would start using new tech after a certain point in time so you could not just stall
They did this in X-COM Apocalypse, and it
broke the game. Early on, you had to be careful of doing exceptionally well, or even just winning a lot of missions poorly, or the aliens would
skip entire tiers of spacecraft that you needed to shoot down, capture, and research, resulting in a broke game that you could never complete because you're missing that
one UFO type needed to produce a certain vehicle or piece of tech you need. You could miss out on the necessary research topics to create the Dimension Probe, which you can't complete the game, or develop alien-based aircraft, without.
BTW - they didn't do this via research. They actually tracked a score that was based by how many troops you lost/kept alive on your missions, whether you won or lost, how many aliens/enemies you took down, how many UFOs you shot down on the cityscape, how much research you finished, and how much alien infiltration you allowed in other organizations. The higher your score was at the end of each monthly period, the more your funding would be adjusted (higher score = more funding) for the next month, and the faster the aliens would progress up the tech tree, up to and including skipping entire tiers of technology. The Alien Dimension was reset monthly (with the exception of destroyed alien buildings) and the UFOs and aliens populating it would be determined by your score.
Trust me, things are better off how they stand. At least you can't screw yourself and make the game unwinnable just by playing well.