The main reason why you should purchase products with ease of scalability because you, as a business owner, would like to eventually grow your business.  That means that your single router, share point server, etc, etc wont work when you have more than a certain amount of users.  The bigger concern is that as you grow, you will pay for all kind of fees for having more and more individuals on certain products.  Lastly, you want to ensure that there is an adequate amount of payoff per employee which is vital when you have scalability.