This is a lazy statement based on extremely vague handwaving about desktop v.s. web. It's not the 2010s anymore. Time to drop these generalities.

Users were migrating to us _from_ desktop applications. Collaboration was the key differentiator, but a less well known reason was that improved performance, including but not limited to the support of large design systems, was also a commonly cited reason among paying customers for migrating to Figma.

A native application that further locks users into some single platform? Or accept all the maintenance and development costs and burdens that keep the application one step behind Photoshop if they wanted to support multiple platforms?

They explicitly had the goal of being a web application. It was a product choice, not a technical choice.