This is not by any means solely a bean-counter forced move. It is sadly a generalized movement to where volume is and not necessarily profit. In the SMB space, vanity in having a major client to talk about, as though it will raise their own profile or cause others insane jealousy is at fault.
A critical factor too is the loss of traditional salesmanship and sales or account management where most time today time is spent producing excel spreadsheets instead of selling or managing teams. Historically, while revenue growth streams were there, it was less of a problem but more recently, it carries a terrible sting in the tail.
Increasing customer breadth delivers greater stability and consistency and opens up new avenues of business activity. Using your clients to tell you what to sell is absolutely critical today.