Comment by adrian_b

There are many cases when the incremental change that is due to an individual inventor is very clearly defined, so it is known precisely which is the contribution beyond what was inherited from the predecessors.

For that incremental change, the name of its inventor is appropriate.

However, you are right that too frequently people fail to distinguish what was new and what was old in an invention, and they misleadingly attach the name of the inventor/discoverer to the entire big system or theory, not to the small features that are truly new.

The inventors or discoverers are frequently guilty of this themselves, by failing to properly acknowledge their sources and by making exaggerated patent claims, which nowadays are too frequently accepted by patent offices that do not perform an adequate search of prior art.