No, because most assignments aren't really to test understanding but for different pedagogical goals (you could go down a rabbit hole of educational theory about different types of assessment and how and why they are used in different circumstances).
In quite a few courses a key part of the actual valuable learning work is expected to happen outside of the classroom by practicing some activity or putting in time&effort to creatively think about some topic. And for many students this work happens only if there are adequate means for controlling that it has been actually done. So if students can trivially fake having done the practice or thinking, that course design isn't working any more, and you need some completely different structure of the coursework or activities so that the students will put in that work required for the learning outcomes.
Like, if someone assigns an essay about (for example) the impact of foobar on widget manufacturing, it's not because anybody cares what the students think about this topic, and (in most courses) not because they want the students to practice writing essays, and not even to evaluate whether students know about the impact on foobar on widget manufacturing - usually the goal of such an assignment is to (a) have students put in some time to read and think about these topics as a whole, and (b) to see if they have some specific misconceptions that should be corrected with feedback (which is substantially different from testing the level of understanding - if you'd want to do that, then probably a different assessment type would be chosen, formative vs summative assessment).
If the student has someone or something else write that essay, both these goals fail - but these things are needed for the course, so now the course needs to be redesigned to throw away the essay (because it spends time but doesn't contribute to the goals due to it being faked) and add some new activities that will achieve these goals - for example, extensive in-class discussion or debates that will require preparation and will reveal those misconceptions. But that requires changing how that course is taught, which takes time and effort.
If people don't want to learn, let them cheat themselves. Just that grades (and what determines whether a student gets to go to a good university) should be graded 100% in person.
In quite a few courses a key part of the actual valuable learning work is expected to happen outside of the classroom by practicing some activity or putting in time&effort to creatively think about some topic. And for many students this work happens only if there are adequate means for controlling that it has been actually done. So if students can trivially fake having done the practice or thinking, that course design isn't working any more, and you need some completely different structure of the coursework or activities so that the students will put in that work required for the learning outcomes.
Like, if someone assigns an essay about (for example) the impact of foobar on widget manufacturing, it's not because anybody cares what the students think about this topic, and (in most courses) not because they want the students to practice writing essays, and not even to evaluate whether students know about the impact on foobar on widget manufacturing - usually the goal of such an assignment is to (a) have students put in some time to read and think about these topics as a whole, and (b) to see if they have some specific misconceptions that should be corrected with feedback (which is substantially different from testing the level of understanding - if you'd want to do that, then probably a different assessment type would be chosen, formative vs summative assessment).
If the student has someone or something else write that essay, both these goals fail - but these things are needed for the course, so now the course needs to be redesigned to throw away the essay (because it spends time but doesn't contribute to the goals due to it being faked) and add some new activities that will achieve these goals - for example, extensive in-class discussion or debates that will require preparation and will reveal those misconceptions. But that requires changing how that course is taught, which takes time and effort.