As someone who has had to do deep code archeology, "this was finished before coffee kicked in and is suspect" or "this was written before lunch and the coder may have been hangry" can be really interesting information to have.

git bisect supports --first-parent and bisecting a noisy history is not just possible, but often faster with --first-parent. When you find the merge commit that introduced the regression you branch that commit and run git bisect --first-parent in that branch for additional drilldown into which "sub-commit" of the merge introduced the problem. (And you can do that into additional layers if you've got deep merge commits.)

> You could, but it's thoroughly nonstandard and requires knowledge and careful use of tools to filter out all the noise.

It doesn't require that much "care" to use --first-parent as a default in your git commands. You can even set it as a default in you git config for relevant commands (like git log, git praise, git bisect), or just add simple aliases for them. Pretty standard, and not that much knowledge, and you can pass it around with a couple quick git config commands. Assuming of course remembering the pretty much only one option --first-parent is too hard.

Also, I don't know what "care" has to do with it: forget to do it and you see a lot of "noise". Noise isn't dangerous. Annoying maybe, but it's definitely not dangerous to see extra noise when you wanted a cleaner view.

Outside of the command line, sure there aren't a lot of great UI tools that take a --first-parent centric approach to git. But it doesn't need all of them to "agree" (because again, if a tool shows you too much noise, that's not dangerous, that's just annoying), just one good --first-parent based drilldown UI would do a lot to make people more comfortable with thinking about the git log in two dimensions instead of trying so much to squeeze git into the one dimension of CVS or SVN. I think it's mostly a matter of aesthetics and what "sells": the subway diagrams of the DAG look pretty in screenshots but rarely are a great user experience in practice. (So much so that everyone keeps wanting to smash git into a single dimension of code history because they find it too "noisy".) Rather than "declutter" with rebases, a --first-parent / drill-down-oriented UX would do wonders for the git ecosystem, especially for Junior Developers uncomfortable at the command line, that likely shouldn't be trusted with rebases, and would have a much better time all around if told them "don't sweat your individual commits, they'll roll up into a cleaner merge commit at PR time".