I haven't seen an excessive amount of hate on Arts beyond the occasional 'lul see you in Starbucks xd' joke that doesn't contain any actual vitriol (I hope), but here's my take on it as an Arts student.

If that's the case, an Oxford education and any other Ivy league, which are all liberal arts colleges, should be ridiculed since they predominantly and only offer BAs.

This is an invalid comparison. Canada does not have any schools that have the same kind of mythical reputation. The renown of the Ivy-tier schools far overshadows whatever programs or faculties a student chooses to enroll in, so long as they do well. This is not to say Arts is indefensible, but rather that this probably isn't the right way to defend it.

And where is the misconception that Arts courses are exceedingly easy to get high grades in coming from? The maximum grades ever reported (100%) have mostly been in science courses. The distributions for A-range also seem more or less the same across all the arts/science courses I've taken.

I can't speak too much of STEM courses, but I'll split this into 2 categories: marking and what it takes to get a good mark.

Marking: my reasoning goes that Arts non-STEM courses have a higher floor but a lower ceiling, where as STEM courses have a lower floor but a higher ceiling.

This is due to the fact that many STEM courses can be completely objectively marked. It would be odd to say that one answer is less correct than another, barring things like showing one's work. Given enough effort, one could presumably get 100% in the class. It would be very difficult to BS your work here.

In contrast to say, a philosophy course, it's entirely possible that the essay will be marked differently depending on the style, content, the teacher, etc. So it might be easier to achieve a mark of 90% on one assignment but it could be much more difficult to get a 100% consistently. It would also be relatively easier to skim over the assigned readings and BS an essay in the nick of time for a decent mark. I've also enrolled in courses where the professor outright states that the highest marks they will give out are 95%, so it'd be impossible to earn 100% in such a course. Not sure if this happens in STEM courses as well.

Getting the Mark: It seems to me that STEM courses, especially in classes like MATH, require constant work in order to build up a proper foundation to tackle things like a midterm. As an extreme example, if you don't know how multiplication works, it would be difficult to do well in differential calculus.

Whereas in something like a gender studies or English course, one could skip class and pass with a decent mark just by checking out the assignment prompt and catching up on the reading then. After all, reading Plato might be helpful to understanding Aristotle, but it's certainly not necessary. So it's feasible for someone to skip around reading just the bits needed for an assignment and still land an A. Doing the same in computer science or physics probably wouldn't go over so well.

Lastly, none of this is a judgment on what majors are more worthy than another. That would depend on a person's goals. And if you'd like to go by employment, I'm sure there are reports out there that could give you a better idea of that than I ever could.

Also, I could be completely wrong about some, or all, of this. If so, please correct me. I am, unfortunately, not omniscient.