1:1 scale ?
I’d strongly advise keeping all W2s and, if you’re an independent contractor, 1099s.
If you’ve worked at companies that have gone out of business, there’s no way for a prospective employer to verify your past employment.
However, if you’ve kept the W2s/1099s from those defunct employers, prospective employers will accept them as proof of employment. At least that was the case when I applied for my current job at a Fortune 500 company...