You could disable the squiggles in Word, you know.
> The care and attention to the resume (which the candidate has time to prepare and consider) is used as a proxy for the care and attention that a potential employee will pay to the code base.
It is very often used as a proxy. That doesn't mean it is an accurate proxy.
If I've got more resumes than time slots to call back on, its necessary to filter them somehow.
When the word processor that the person used is flagging things as misspelled, or grammatically incorrect - the person didn't use the tooling available.
I've had resumes where one section was indented and bulleted, and the next section was numbered rather than bulleted... or indented without bullets or numbers (just a tab - that has a line wrap go to the left margin rather than the tab stop like the bullets and numbers in the other section).
Many of the things I've seen aren't an accidental oversight but a deliberate choice in the formatting of the resume that is wrong or inconsistent with a very short glance.
I mentioned in another comment that I've seen a resume where various keywords were bolded (annoying, but common). Among others, the word "Java" was bolded. "Worked on Java microservices using Spring Boot". Ok. However, Java was also bolded in "Used NodeJS to write JavaScript backends" - "Script" was left unbolded.
The accuracy of the proxy is less of an issue when you are able to find at least the number of acceptable resumes as there are time slots for interviews.
> The care and attention to the resume (which the candidate has time to prepare and consider) is used as a proxy for the care and attention that a potential employee will pay to the code base.
It is very often used as a proxy. That doesn't mean it is an accurate proxy.