Most of the hosting companies are now offering Unlimited everything, like Disk Space, Bandwidth, Addon-Domains, FTP Account, Databases etc...
But you really can use hundreds of GBs of Disk Space or Bandwidth?
Answer is, simple NO
Why?
Almost all large and reputable hosting companies are using CloudLinux App. So with CloudLinux they can restrict the resources that an account can use, like
1 or 2GB RAM per Account
20 Concurrent Connections
CPU Usage Restrictions
Disk I/O Usage Restrictions
So if a use is on CloudLinux based Server, he will be restricted to the allowed resources only and can not use more resources than that.
So basically, if one website is having visitors around 1k to 2k per day or 20 to 30 concurrent users at same time, the max disk space usage of that account increases to 2 to 3 GB or sometime 4 to 5 GB, depends on the Images he is using for his website. (CMS Based).
Max Bandwidth he will use is about 20 to 30GB Max on that time.
With that much traffic, a normal account will easily consume 512MB to 762MB RAM more or less. And sooner he will starts hitting to his limitations.
And if he is using couple of Addon Domains in same cpanel, with same amount of traffic, he will ran out of his resources soon.
In result, he will get errors on his website about Resources usage, and sooner or later, his provider will suspend his account.
So basically for a normal usage website, you really dont need Unlimited Disk Space and Unlimited resources at all.
Its just a market gimmick or a business term. Nothing else.
Most of the Unlimited Providers are having more issues than the ones with limited packages.
