These companies hire out third parties who are very aggressive and often use half-assed automated systems with no oversight to find "infringing" content. They don't care about the accuracy of their notices. They know most people won't know how to combat this or won't risk the fallback from the platform if they try to fight it. The platforms themselves make their process convoluted and automated because they don't want to pay a person to deal with the flood of DMCA notices or the complaints from their users who are getting screwed over by them. It's very telling how often these things only get resolved once it's publicly posted about on social media. Support shouldn't be something users can only get if their complaints get enough likes/views/upvotes on other platforms.

The companies carelessly sending out DMCA notices just want big numbers they can put in reports to the people paying them. "Look how many takedowns this month! Your copyrighted works are so popular and everyone is trying to steal from you! Better keep paying us for protection!"

Actual DMCA notices are sent "under penalty of perjury" and with a "good faith belief" of accuracy, but nothing happens when they do this shit anyway. Platforms can act on any request even if it's not a proper notice under the law just because it's easier for them. Until copyright holders start seeing severe consequences for abusing copyright law this is just going to continue because it's profitable for them to screw over the artists whose works get attacked.