Copyright is a mess and yes even sounds can fall under the hammer of the Youtube algorithm. Fair use wise if you purchase the sound assets or pay the royalty fee you are covered under common copyrights or fair use. This can effect Streamers as they usually do not pay any kind of fee to broadcast copyright works as being in the same category as say a radio or television station.
Since most Streamers are monetizing their streams if you use someones assets they can make a claim, without YouTube issuing a strike against your video but you loss any form of monetization and goes to the copyright holder. The issue is not your rights to use it but an algorithm that has no clue if you paid for the rights in the first place.
Their are other issues, like “Let’s Play”