Or overvalued the business and/or assets. “Welp, no one wants to pay asking price, nuke it” when it could’ve lived on as a one person shop at a lower sales price.
If the value of the site were enough that they could make any money after transaction and transition costs, they would likely have taken that step. Given the time horizon on which they are shutting down, I would guess that they have been out of money, and that the service makes less than it costs to run even with a skeleton crew. Another comment in this post cites information that confirms this.