The position of Scoutmaster is separate from the Young Men’s organization. Advisor’s are sometimes called as assistant scout masters, but the SM is it’s own.
I have served as a SM. I have also served as the Y M President. While the example you sited might happen if no one else is available, it’s not typical.
Not to get into a tit for tat or anything, that may be how it is on paper, but not in practice at every ward. If there aren't enough adults, the SM is usually wearing the advisors hat as well. I've seen the YM's org run roughshod over the SM and undermine Scouting programs within wards. It happened to the Troop I was trying to help here in SoCal, and to the Troop of a friend of mine (active LdS). I can go into further detail if you're interested, but not here, too long of a story.
"While the example you sited might happen if no one else is available, it’s not typical."
I believe I said "isolated incidents" and in no way was I trying to imply that it was typical. I was merely addressing one of the points of the article and questions others on the thread had asked as well.
I know and am friends with many LdS Scouters and the problems within LdS Scouting are many and IMO, easily resolved.
I was an LdS SM twice, once in SC as an active member and once here in SoCal as an inactive member. The problems were almost identical. Lack of parental support, boys and ward leaders dismissing the program as subservient to the YM's program to name two.
There is great potential within LdS Scouting and it may be that in large LdS communities, that potential is achieved. Outside of that, I have personally witnessed many lost opportunities.