I'm not going to reply to any specific comment because my response is not directed at anyone. I think it's wild that the general public actively discovers and will plan to buy from a private farm. In every other area of agriculture I have experience this is a radical mindset shift and a fascinating market model. Building personal relationships and direct to consumer sales has been a pipe dream for farmers for decades.
That being said, you have to be really creative to even guess what the market demand is. There is no public market or commodity reports for tubers. Hobbyist and farms get one sale a year to see how things land. There is no test available to push the boundaries of a website during a sales drop.
Sellers can only manage what they can control. They can control their market to a degree. Some sellers choose to limit who they sell to. Some will not sell online. Others will create a (monetized) community. A seller can control pricing. Sellers can choose not to communicate with their customer base and silently open sales in an effort to avoid tech problems. Each one of these has positives and negatives.
I've tried finding a similar business model to the dahlia market and one does not exist. There are a couple of niche products (net worth usually 100+ million) that have a fanatic fan base but they can always manufacture more product throughout the year. They solve similar problems by spending a lot of money. Guess what? They still have checkout failures! They still have angry social media comments.
It's ok to feel disappoinment. It's a broken system on both sides. A seller will need to think outside the box and put themselves in a vulnerable place publicly to modify customer behavior and influence the market. If a seller were to step out and try something different they get one shot. Failure is more common than success when you try something new for the first time.