Agreed: I highly recommend it.
> there's usually one glaringly obvious mistake in nearly every single article
An actual mistake or a typographical error? It compares very favorably to the error rate in Donald Trump tweets!
> they never seem to issue corrections,
The Guardian is famous for publishing a "Corrections & Clarifications" column , and collected clarifications have even been published in book form .
However, typographical errors are rarely included, though they do get corrected on the website.
> so screenshotting is pointless
Yes, screen-shotting is pointless. However, you can email the quoted line(s) and a link to the Guardian global readers' editor at email@example.com
Hope that helps!