I would say the coaching route usually goes through juniors, pros, or assistant coaching prior to D1 head coaching as well. Same as a lack of roster spots for players, there is also a lack of coaching spots at the highest levels for the number of coaches who could do it. In addition, those were just 2 coaches I pulled off the top of my head, being that they run perennial powerhouses, Stonybrook being another one.
Many players actually turn down NCAA D3 offers to go ACHA due to a variety of factors (tuition costs, grades, desirable school/location, degree programs offered, familiarity with the coach, expanded roles, eligibility, etc). I would know, I was one of them a few years back.
Side note, MK, what is your affiliation with LU? Fan, player, parent, staff?