fritzo parent
The world of viruses is wide and beyond our current understanding. 50 years ago one might have dreamily wondered whether "eliminating all bacteria" would improve the world. Now we know we'd all die quickly without bacteria (e.g. gut biome). I think we're about at that level of understanding today regarding viruses.
There's a hypothesis that a viral gene made mammalian placenta possible: [pubmed](https://pubmed.ncbi.nlm.nih.gov/10693809/).
And there's not even the only one (there are other syncitins).
Disclaimer: I'm not a medical professional