> But something also got lost along the way, and it's that obligation to read slowly, to understand every line because there was no shortcut available

Not really sure what got "lost" here. But fundamentally nothing has really changed much, except for deeper abstractions, more powerful tools and the cost of "generating" (or producing) code approaching near zero (if you discount the cost of subscriptions to Claude/Codex, etc and the underlying costs of running those st scale).

You still have to understand, and read every line. Although now we just get tools to do so for us. But the understanding is still a requirement.