Even if every studen have zero prior knowledge in a course, there will be those who will perform better early on being able to understand the course faster than others, of course you should grade that ability.
I've never looked at how long someone was in college, and honestly don't care if it took them 4 years or 10. I assume there's a reason it took them 10, and that could be lighter class load, a change in major, or all manner of things. If it's because they took every class 2-3x, because the first time it didn't stick, it'll show up in the interview process that they can't pick things up quickly, and I can do what I want with that information.
But to the grandparent's point, if I gave a leetcode problem (I don't), and someone immediately coded the ideal solution effortlessly, which tells me they have seen that problem recently, I'm not going to just be like "yep, hire this person, they're clearly a great engineer!" They're great and/or lucky at test prep, which is not the skill I care about.
If this is your viewpoint, I can only conclude that you're from an elte family born into money.
The rest of us go to uni to get a higher paying job and avoid wage-slavery and/or poverty.
And if this is you, ewww https://gfmsouthwest.org/ Academics, work and "jesus" have no place together.
This hasn't been true for probably half a century, possibly longer. The number of people who go to university simply for the learning experience is almost certainly vanishingly small.
If you look, for example, at the completion rates of non-college courses like you'd find on Udemy, etc. It's <10%.
You would also expect audit rates to be much higher for people looking 'just to learn' - auditing classes is typically significantly cheaper than paying full price for the course.
People go to school because they are looking for an edge in their long term earning potential (types of jobs, credentials leading to higher salaries, etc).
One student gets 30%, 60%, 90%, and 100% on a series of four cumulative projects throughout the semester while another student consistently gets 70% on all four.
I would argue that the former likely has greater mastery and certainly has learned more during the semester. If you want to make sure those two things (mastery and learning ability) are measured by the final grade you need to use some method that de-emphasizes the earlier grades.
Are you seeking signal and view this change in grading style as noise? Do you really believe this style of grading captures merit? What does the grade represent? What is the point of this exercise for you? Are grades just for deciding which student to give the best spoils to?
In practice I've found that many of the students who are at the top of the bell curve after the first test are the ones who have the most prior familiarity with the subject matter. Whereas the fast learners are typically the ones who are at the top of the curve at the end of the course.
In this context, equally-weighting early grades has a higher probability of penalizing the fast learners than it does of rewarding them.