Honestly, I don't think this is true for the top EA cause areas. These have been selected for impact and not for utilizing people with a wide range of backgrounds and preferences.

OTOH, it's pretty self-evident that people can do "the most good they can do."

Direct work in the top cause areas is a relatively narrow interpretation of EA principles. And, personally, I find the broader interpretation more encouraging and even somewhat relaxing.

Why not encourage students to experiment for themselves? Try a summer internship or volunteering or taking a class on a topic where they could help solve one of the world's top problems, as well as exploring areas they've been drawn to since childhood, and keep an open mind as they explore.

I think a lot of people will find it really satisfying to see how they can help people, but some people might genuinely be happier working on something they've been interested in since childhood, and we shouldn't try to deceive those people!

I believe this primarily due to arguments in So Good They Can't Ignore You by Cal Newport that suggest that the application of skills we excel at is what leads to enjoyable work as opposed to a passion for a specific job or cause, but also because I think that community & purpose is super important for happiness and most top EA causes seem to provide both. 

I think this is often a real tradeoff, but there are other ways of framing it that might help:

A) You should work in something you at least somewhat enjoy and have a good personal fit for in order to avoid burnout (I think this is 80k's position as well). Within the range of things that meet this criteria, some will be more impactful than others, and you should choose the most impactful one. EA frameworks are very useful for discerning which one this might be.

B) The aptitude-building approach (from Holden Karnofsky's 80k podcast episode): You should become great at something you like and are very good at, and then wield it in the most impactful way you can, which knowledge of EA is again useful for. (Even if it is not initially obvious how, most skills can be applied to EA in some way—for example, creative writing like HPMOR has served as a great tool for community building.)

If someone is unwilling to move away from a low-impact cause, there are still ways EA can be useful for helping them be more impactful within their cause. Similarly, if someone is set on a certain skill, EA can help them use it to do good effectively. 

This article by 80,000 Hours on job satisfaction is probably a useful resource on how working on the most pressing problems doesn't necessarily have to involve sacrificing happiness.

Cal Newport argues in favor of this in his book So Good They Can’t Ignore You, as a uni group leader myself I’ve found his points useful when talking with new members.

I believe Cal Newport’s career advice has been quite influential in 80000 hour’s own, so you might not find anything terribly new there but I do think it’s worth checking out.