Companies Utilizing Solely Non-GAAP Measures on their tables – Why? More Risk?

Hey all, I've been digging into some earnings statements to bone up on my corporate financial chops/understanding, and I'm seeing a number of companies that post both GAAP and Non-GAAP spreadsheets for cashflows and income statements – hell, some companies don't even have GAAP measures at all.

From a historical perspective, how common is this for auditing practices for publicly listed companies? I get that there are instances where Non-GAAP measures can provide insight into various factors that traditional GAAP measures don't, but does relying solely on Non-GAAP measures present added risk to proper valuation for a company's stock?

Any insights on this would be helpful. Thank you!