I wouldn’t say the “quality” of research is lower at LACs. It’s just that the projects are usually smaller, fewer, and more constrained by available resources. The available resources (including time) depend on the school.
Imagine profs at an R1: they’ve all done a PhD and usually at least one postdoc. They barely teach, they got startup funds, access to institutional equipment, and should have grant funding. They can get trainees and staff to run their experiments. So research productivity is high. Undergrads mostly do scut work, but a few have projects.
Profs at an R2: all of that same stuff, but fewer research resources, and some more teaching. Research productivity medium high.
Profs at a fancier LAC: decent startup funds and some institutional equipment. They occasionally have external grant funding. All help is from undergrads, many of whom have full projects. They probably teach 2-3 classes per semester. Research productivity medium.
Profs at a not-fancy LAC: modest startup fund, institution may have little equipment. They occasionally have external grant funding, and many profs at this level have still done a postdoc. They likely teach 3+ classes per semester. Research productivity medium or low.
LACs hire profs that have ideas for projects that are possible on a tight budget, using only undergrads for help. You shouldn’t get tenure if you’re a bad teacher at a LAC, and you need at least some research product. At an R1, if your research/funding is sufficiently plentiful (not necessarily high-quality), you’ll get tenure even if you’re a bad teacher.
So the research product from LAC profs is still good quality, there is just less of it. The techniques aren’t as flashy, trendy, or expensive, but are solid. They get really creative. They have impressed me at conferences with the ingenuity of their projects. Many LAC profs do research at other sites, including with collaborators, where they can access resources they don’t have at their own institutions. They like to involve students in this when possible.
I have not observed a strong correlation of research quality (it takes an experienced scientist to assess this) with institutional size or prestige. In my field, there are a lot of eye rolls when certain folks (not all!) from UCLA, Yale, etc, get up to talk about their work. Because it’s flashy but not high-quality, and there’s a lot of posturing (again, certain people, not all!). I’ve seen poor-quality research (sloppy, wasteful, wrong, dishonest, etc) come out of researchers across the spectrum of institutions. Good ideas are a dime a dozen, it’s the implementation that’s important.
All this is to say: a student can be well-trained in high-QUALITY scientific research (careful, efficient, accurate, honest) at any school. They just need mentors who know how to do it and teach it. And those can be found at any institution. That’s why a LAC can prepare an undergrad well for a PhD.
Edited to add: By saying R1 profs “barely” teach, I mean quantity of teaching, not quality of teaching. A “trainee” in a research lab is a student or a postdoc.
) PhDs generally don’t get any type of pay bump for having that degree. So…that’s just a huge opportunity cost for all those years of not making $, not getting work experience, not getting promotions…blah blah blah. I get that some bench research jobs really value PhDs, to each their own!