I already use uMatrix, but why should I trust 1st party scripts. I regularly visit less-trusted sites or sites that I never visited before, and I wouldn't want

I already use uMatrix, but why should I trust 1st party scripts. I regularly visit less-trusted sites or sites that I never visited before, and I wouldn't want them to be able to just execute Turing-complete scripts with access to potentially a lot of information on me (only just the browsing history would be a lot) on my machine or that can trivially fingerprint me.