Anyway, CSS could be considered a mess, especially for layout, but given its history, it's quite reasonable. I worked on something where every element had absolute positioning in the browser. That gives excellent control over the layout, but leads to all kinds of other issues. Flex and grid are two easily understood, productive solutions to the general problem, just not 'perfect'.
Sorry, by scale in this context I meant "used by a large number of users". Obviously there's no risk in CSS itself scaling - more that there's risk in using CSS Grid to the degree they have in a way I haven't seen in many web apps.
Maybe it means "automatically" (?). It seems like a bad excuse to have a tool automatically output bad CSS. If the CSS is not as good as written by an expert, then there should be a good reason for this like "theoretically impossible to know what the user wants from available specified info in the tool". Otherwise the tool is not doing such a good job.
There have been tools to output CSS forever. The only question is, whether output is appropriate. If it is a mess then it can only be used for fire-and-forget prototypes.
What does "at scale" mean in this case?
Anyway, CSS could be considered a mess, especially for layout, but given its history, it's quite reasonable. I worked on something where every element had absolute positioning in the browser. That gives excellent control over the layout, but leads to all kinds of other issues. Flex and grid are two easily understood, productive solutions to the general problem, just not 'perfect'.