This article is more than 6 years old. Plaid helps some of the highest-valued apps in financial technology connect their users, its connections to banks providing virtual piping for the likes of Coinbase and Venmo. Now, after a $250 million fundraise, fintech’s plumbers are worth more than many of their better-known customers. The large-sized investment in Plaid is the first notable check by investor Mary Meeker since she announced she would leave Kleiner Perkins Caufield & Byers to start an...