Is it a good idea for people to serve SMBs before moving enterprise businesses?
Yes, it's a great strategy. When selling to SMBs, you end up spending a lot of time focusing on the end user. If you cannot convince an individual to buy your product, then the product isn't good enough.
Eventually once you are ready to move mid-market and above, you will have to learn how to sell to the CIO, and to integrate their opinion into the platforms being used.