Life Insurance is useful in some rare circumstances. It IS mustachian to use it after calculate the cost/benefit and take decision. As csprof said, it is an edge against a low-probability but high-cost event.
As an example, a couple with 1M$ NW may not need life insurance from our POV. On the other end, they can afford a 500k life insurance for 500$/year because it's pocket change for them. One of the spouse die and there is taxes to pay. Lets say most of their NW is tied in real estate (or a small business, or wathever) wich mean you have to borrow against to pay the taxes or sell (at profit or loss?) wich take time, carry fees, and afterward may not be the best decision. Life insurance money will give the liquidity, time and at the end, choices. To me, this is kind of mustachian.
And what if a couple with children, 1 low income parent (spend a lot of time taking care of the children, house, meals, etc.) and 1 high income parent (work with a shitty schedual, long hours, travel a lot, etc.) They manage to do pretty well on the mustachian path, 50% saving rate, etc. One of them die, this change the "pattern" and you cannot think this will not hurt in any ways (both personaly and financialy). Life insurance may prevent from things like "find another spouse for money or baby sitting purposes" at least in the short term.
In our plan, we will spend about 10k on life insurances over our working career and bring home 2.5M wich mean life insurance cost less than 0.5% of our income to edge the death risk.
To me, it fits in the same category than keeping 500$ in cash at home and 5k in the checking account when your investing portfolio is 1M. I would say it is a bad choice for someone with a 5k balance on CC @ 18.9% and a 0$ NW. Same money, different decision!