This is one issue that I'm passionate about. Research increasingly implies that homework is probably harmful in elementary; of dubious value in early middle school; and only valuable in high school and beyond.
> and objective performance assessments
I think some of these radical experiments are crazy. But, there's valid reasons to consider e.g. not grading missing absent assignments as a zero. A few of them:
A) If our goal is for grades to reflect demonstrated student mastery --- a missing assignment doesn't indicate that proportion of mastery "missing." Especially if it has been demonstrated satisfactorily on an exam or by other measures.
B) A couple zeroes on a gradebook can be an insurmountable hill to climb-- leaving no further grade incentive at all for students to work hard in the class.
C) Grades are strong motivation for already-strong students with the most involved parents, but can actually be demotivating for the bulk of your class. An effective teacher needs to find other ways to motivate students. For many students, grades are something that can make one feel bad about oneself but not provide an opportunity for positive differentiation.
The classes I teach are "easy A's" in the gradebook for most of my students... and are incredibly demanding compared to normal MS/HS fare. This requires buy-in from my students. I work to build genuine curiosity and in-class competition (on a variety of axes where all students can excel, not just the top couple dunking on everyone else).
It’s so frustrating how worthless it all is too.
For my boys, we went outside school to various providers of math offerings for gifted kids. But quality is rather variable.
Being ahead academically doesn't mean you're ahead developmentally. Rote practice to avoid mistakes and do really systemic work is useful sometime around ages 12-14 -- during first algebra classes for kids on the normal plan. But courses for gifted 10 year olds taking Algebra I at e.g. CTY tend to lean even more into the "rigor", which my kids survived but it was unnecessarily difficult. Instead, they should be looking for ways to shorten problem sets and approach problems from various angles.
That is, whether you can keep a 9 term polynomial straight and avoid swapping signs or coefficients is really a measurement of attention span and focus, not understanding of algebra... and students that are way ahead in math are probably slightly ahead in attention span and focus, but not to a degree commensurate with their mathematical knowledge.
(We really like Art of Problem Solving, though it's pretty intense).