General purpose build systems need to make API expressiveness, observability, performance, and correctness tradeoffs in exchange for their platform breadth.

By narrowing breadth, most often by targeting only one ecosystem[1] or making correctness tradeoffs[2], new build systems can be way more expressive and performant. For now.

They’re also fun to write because DAGs are parallelism are cool problems to think about.

[1] e.g. only targeting one language allows you to use that language instead of a generalized DSL to describe your build graph [2] e.g. abandoning sandboxing altogether and using manual invalidation or just trusting the user