An H1 is the clearest "this page is about X" signal you control, and it's also one of the easiest things to get wrong without noticing: a template that gives 4,000 product pages the identical heading, a page with no H1 at all, or a third-party widget quietly injecting a second one into the DOM. TechySEO checks every page for all of it.
Google can infer what a page is about from body content alone, sure. But the H1 is the most direct, unambiguous statement of topic you get to make on the page, and skipping it on a page that matters is leaving a free signal on the table for no reason at all.
Run three H1s on one page and you've basically told Google the page is equally about three different things, which usually means it's not clearly about any of them. Run the same H1 text across fifty different pages and those pages start competing with each other for the same keyword position instead of each owning their own.
Length matters too, just less dramatically. Past roughly 70 characters, every extra word dilutes how much weight your actual target keyword carries. Keep it tight, not because there's a hard cutoff Google enforces, but because a long H1 usually means the topic isn't focused either.
Not just "does an H1 exist." Whether it's unique, focused, and actually agrees with your title tag.
Run the audit and find the missing ones, the duplicated ones, and the one that turns out to be a chat widget's accessibility markup.