It somewhat encourages companies to act this way by making it the safest path, but it absolutely does not force them to. Service providers are not required to act on invalid dmca requests.

Consider wikipedia which regularly rejects most [1] of the dmca notices it gets because it cares enough to actually read them and ignore the ones that are bullshit.

[1] according to https://wikimediafoundation.org/about/transparency/2023-1/dm... in a 6 month period they got 29 dmca requests and ignored 27 of them.