Unfortunately, the (software) patent system does not distinguish between people actually innovating and rent-seekers. Patents very explicitly give their owners broad rights to shut down any use of their patented inventions through injunctions.

If you think that the MPEG-G patents are not going to be enforced in case someone was already doing what they were doing before the patent was granted, well, have I got a bridge to sell you...

As for MPEG-G creating value, I think that is highly debatable. See this post: https://datageekdom.blogspot.com/2018/09/, which summarizes the MPEG-G situation as "Patents + extensive high profile marketing + lack of evidence for benefit".

That's not a valuable contribution to society. It's simply a tax on the bio-informatics community.

That's sometimes the case for software patents in general, but not for patents tied to a standard like MPEG-G, where the point is to get people to pay for being compatible. I've looked at a couple of the MPEG-G patents, and if you're infringing the MPEG-G patent it's probably because you're actually using MPEG-G without paying for it, not because you happened to independently recreate the same thing.