It's because you can only fool your customers/clients for so long before they realize your product is garbage. If you have poor quality you need to have a lot of support staff to deal with the calls/emails or you need to have deep pockets to offer discounts and refunds repeatedly.

It's so fucked to read about VC-funded startups and read Paul Graham's earlier essays because he pretty much summed up a startup as "move as fast as possible to build a product that your customers want" and emphasized quality. Somewhere along the line, getting VC funds somehow has dwarfed that goal.