IMO, "20 people had a five year old with progeny" is a frivolous rationale.

Of course, there are a number of poor quality trees at ancestry. There are also a lot of high quality trees at ancestry. It's easy to find mistakes on genforum, rootsweb, family search, family tree, etc.

It takes 2 minutes to determine that the other line is garbage, as in your example. Ancestry software should be able to eliminate your example from consideration programmatically.

If ancestry has 1,000,000 trees with DNA results, IMO it would be foolish to ignore all of these trees, because some trees are poor quality.

I checked a match today, where the other line has two mistakes in that they have the wrong ancestor in the line. Also, they are missing documentation for the relationship between a son and his parents. In two hours I was able to identify the corrections to the other person's tree. They are definitely descended from the common ancestor based on a paper trail. The other tree owner simply needed help.

This does not mean that I agree with ancestry that their business model does not support the cost of developing a chromosome browser. If they really have 1,000,000 DNA kits, a $1M investment based on $100M revenue seems reasonable to me.