Fair point about my source and statement. The main issue I have with your earlier statement is that you say “realizing and describing” equals discovering.
A proper theory at least needs some proof, be it purely theoretical. Otherwise one could argue that people discovered flat earth, there’s plenty of descriptions on how it works floating around. Having purely theoretical proof also means I do not agree that theoretical physicists can not discover things. Einsteins discoveries were all substantiated by rigorous mathematical proofs.

“ Within scientific disciplines, discovery is the observation of new phenomena, actions, or events which help explain the knowledge gathered through previously acquired scientific evidence.”
Straight from wikipedia (page on discovery).
“ In science, the term “theory” refers to “a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.” Straight from wikipedia page on Theory.
So if something is theorised to exist, it is neither a theory or discovery. Both cases need evidence and this has only now been presented.
Within science, someone can not “realize” something exist and claim discovery.