The academic job market is fiercely competitive and can seem arbitrary, much like a HS student seeking admission into a T20 school. The odds are similar if not worse; for one position, even niche categories, it’s not uncommon to see an applicant pool of 100 or more, of which well over half have the qualifications to do the job. It often comes down to perceived “fit” - what will the applicant bring to the position that complements or builds upon existing departmental strengths?
I know plenty of full time adjuncts who are extremely capable and dedicated. Also a common scenario for an academic couple is that one spouse gets the tenure track position and the other has to make do with whatever is available. If we’re talking an isolated LAC, there will be very few opportunities, given how specialized the academic job market is. That does not necessarily mean that the trailing spouse is less competent.
Not all adjuncts are created equal. In addition to the moonlighting professionals described above, those categorized as predoctoral or postdoctoral teaching fellows, lecturers, or visiting faculty (often filing in for regular faculty on leave) generally earn a humane wage, have dignified teaching loads, and will have more time and energy to teach well.
I would hope that private LACs treat their adjuncts better than itinerant adjuncts at community colleges and public universities that earn abysmal rates of pay, especially when one considers the time and expense of obtaining a PhD.
As for the OPs original question, if you are a “life of the mind” personality and aspire to grad school, LACs can be an excellent choice. @TheGreyKing summed up most of the advantages upthread.