Notice that in this sub-topic we're talking more generally about causes for low-quality software -- laggy UIs being only one of the symptoms.

Figma contributes by enabling UI designers to easily author interfaces which look allegedly beautiful but are complex to build, test and maintain.

And the resources burned on building such esthetically pleasant piles of barely usable software could find better use on making it simpler, faster and more focused on user actual functional and non-functional requirements (much of them taking place on the server-side) instead of sugaring their eyes by throwing tons of code on their clients