You are factually incorrect about the well-known DMCA notice and counter-notice provisions. Please read 17 USC §512, subsections (c) and (g). The comment to which you are replying quotes what I presume from context to be subsection (c) (the language is repeated across multiple subsections).
The law provides that service providers can avoid liability by following these procedures, which afford them no discretion or opportunity to review claimed infringement.
You claim that "DMCA claims [...] [impose] a significant legal burden on YT; they would need actual lawyers with actual law degrees who've passed the bar to review each contested copyright claim." From the statute, it appears instead that reviewing section (c) notices or section (g) counter-notices and acting based on their own purported determination of infringement or non-infringement would cause the loss of their safe harbor, a safe harbor available only when the provider follows the nondiscretionary procedure laid out in (c)(1) and (g)(2).
https://www.law.cornell.edu/uscode/text/17/512
The law provides that service providers can avoid liability by following these procedures, which afford them no discretion or opportunity to review claimed infringement.
You claim that "DMCA claims [...] [impose] a significant legal burden on YT; they would need actual lawyers with actual law degrees who've passed the bar to review each contested copyright claim." From the statute, it appears instead that reviewing section (c) notices or section (g) counter-notices and acting based on their own purported determination of infringement or non-infringement would cause the loss of their safe harbor, a safe harbor available only when the provider follows the nondiscretionary procedure laid out in (c)(1) and (g)(2).