Liberal arts colleges can have majors in the professions; that doesn’t make them not liberal arts colleges. What defines LACs is their size, their focus on undergraduate students, and their focus on a well-rounded undergraduate education in the liberal arts and sciences. Swarthmore has an engineering major, but their engineering majors are still expected to get that well-rounded liberal arts education in the context of a small, undergraduate-focused community. Smith has an engineering program, too; it’s still an LAC.
Caltech, while small, isn’t an LAC - because it lacks the undergrad focus and liberal arts-type curriculum. It’s a research university. Rice is another similar place - small undergrad population, but not really an LAC because it’s a research university.
I went to an LAC and now have a PhD. I know lots of professors who went to LACs. There are lots of people from both kinds of backgrounds. In fact, I would say that LACs are disproportionately represented among professors relative to their size in the population. I don’t think it’s because they can’t get jobs so they hide in graduate school, either - that’s kind of absurd. From my LAC (which isn’t even top-ranked), far more people went straight into the workforce than went to graduate school. Writing papers is actually good preparation for lots of jobs, because believe it or not, some jobs actually require you to write (and write papers, even) as part of the job requirements. Not all jobs are at software companies and tech firms - but even at tech firms, not everyone is a software engineer or developer. There are titles like UX researcher (many of which come from social science backgrounds) and technical writer (guess what they do all day long?)
You also don’t need a letter of recommendation from someone famous to go to graduate school; the vast majority of undergrads at either kind of school are not going to be getting recommendation letters from someone famous, simply because there aren’t that many famous people to go around. (Plus, in my field, there are a few famous people at small colleges and smaller research universities.) There is definitely research experience to be had at small colleges, too. The professors at Swarthmore, Pomona, Amherst, et. al have 2/2 loads. That’s the standard load here at my large public research university. Of course, they don’t have the option to buy out and reduce their load (which is what essentially any productive researcher here at my university does), but there is still very much an emphasis on smaller-scale research and involving and mentoring undergrads in that research.
I think that a good LAC or good research university could be, in theory, equally good at preparing students for a PhD program. The key is the individual student, and how they think and what environment is good for them. Some people would flounder at a large research university and need (or want) the nurturing environment of the LAC; others would feel stifled or smothered at an LAC and need (or want) the relative freedom of a larger research university.
Also, I’ve seen undergraduate students at larger research universities get close to professors in research labs - both at a large-ish private university and at a very large public university. It certainly can be done; the students in question just need to be a little more proactive about it.
I’d disagree with that argument. A lot of medical schools are explicitly recruiting humanities majors because they want majors who have engaged with the big questions of our humanity and who often think about medicine more broadly than the science majors they get. One example of that is Mount Sinai’s Humanities and Medicine Early Assurance program.