Some routers might only buffer 1 millisecond of line-rate data or less. If that's the case, that initial congestion window of 10 could overflow the buffer, causing loss and a much more costly double-round-trip to resend.
1 millisecond of buffering is geat on a high speed core link. But if you apply that to a 5 megabit connection you've basically decided you'll only buffer one packet. A slow-speed bottleneck link needs to have more capacity. The charts in http://www.nctatechnicalpapers.com/Paper/2011/2011-right-siz... suggest that 64KB is often a good buffer size for end links, and that can absorb 10 packets fine.
Some routers might only buffer 1 millisecond of line-rate data or less. If that's the case, that initial congestion window of 10 could overflow the buffer, causing loss and a much more costly double-round-trip to resend.