Where your financial controler may see new servers as a nicety, an IPP sees them as a necessity. IPPs have high speed and redundant connections to the Internet. You are hosted with other customers who share the costs of redundant high-speed connections. You set high speed at reduced costs. A web site is useless if none of your customers can get to it.
Computers fail, hard drives fail, connections fail.
The most reliable equipment you can buy can and does fail. Most IPPs do this at a price that you could not afford. Remember that your IPP does not go on vacation. IPPs often peer with all major backbone providers so that if one should fail, they quickly switch to another. This means that they offer dialup access to the Internet.