Simply put:
Hosting option A: Large company, reliable, increased cost to host with them.
Hosting option B: Cheap (possibly a DBA if lucky) --> take your own risk.
If you want to host a website about your pet spider, go with a cheap hosting package for 0.99/month.
Of course, if you happen to be a website like google, having your own data center is more helpful.
Requirements of customer --> how much customer is willing to spend, how much of a risk they are willing to take that the service won't be reliable, and also what budget they have.
Websites about spiders vs. eCommerce sites vs. eCommerce sites for companies with an established customer base...
I guess my favorite line from large companys was always "If its not expensive, it can't be good" and from individuals "Cheap is good".
*sigh*