John,
Fully agree, sounding similar is not copyright infringement. Melody and lyrics are protected by copyright, you can't copyright chord progressions, rhythms, beats, etc...except as a finished work, i.e. loops, samples, etc.. I think people involved in these decision are letting emotion or sentiment dictate the rule of law. How many Country, Motown/R&B, Rock songs sound similar, have similar beats or chord progressions, that could become subject to frivolous copyright infringement cases?
Many new artists are influenced by their musical heroes. How much influence is allowable before you become liable for infringement. If influence and similarity were the bar, Oasis would certainly owe the Beatles a ton of money. A very slippery slope for certain and where does it end? You might be sued by Steely Dan:) Someone generating advertising revenue on YouTube, totally unrelated to selling music, might be subject to a lawsuit of their earnings for "sounding similar" or for offering lessons on how to play a particular song. You can't just look at this as effecting the "rich musicians who can afford it" because eventually a precedent works it's way down the chain to affect everyone one way or another.
Interesting comparison by Rick Beato below - The Gaye estate is suing Ed Sheeran for 100M claiming his song Thinking Out Loud is infringing Let's Get It On. Look at the song as a whole, there may be some similarities and people have strong opinions about it. However, if you were to compare lyrics and melody, there are no similarities. The beat is the same and chord progression are similar but that is it. Very interesting topic and one that seems like it is not going away any time soon.
Rick Beato - ED SHEERAN VS. MARVIN GAYE LAWSUIT: Let's Compare!
https://www.youtube.com/watch?v=0kt1DXu7dlo Regards