I've seen many small to large corporations embrace decentralized storage policies to let the employees deal with their own Exchange Server storage in the form of PST files which is usually caused by lack of storage capacity at the Exchange server. But does this really solve a problem or does it move the problem elsewhere? In my experience, the problem isn't just moved but it's amplified many times.
When data is stored on an Exchange Server, There is absolutely no reason not to deal with the email storage problem centrally. it employs storage saving techniques called "single point storage". This means that the server stores a single copy of a file that's located in multiple emails and multiple mail boxes. This means if someone sent out a 10 megabyte file to 100 people, it would only utilize 10 megabytes on the Exchange Server plus negligible storage space for 100 pointers to the original file.
Organizations that skimp on Exchange Server capacity and force individuals to store their email in individual user PST files end up storing that same 10 megabyte file 100 times in 100 separate computers and amplify their storage problems. A 10 megabyte problem is now a 1000 megabyte problems spread out over 100 computers. Some of those same corporations that implemented these short sighted Exchange Server storage policies also insist on backing up their user data, which vastly increased the backup work load. Not only is it difficult backing up desktop data from multiple client computers, but it's exponentially more difficult to from remote users. Worsening the situation are PST file corruptions on individual desktop machines that jacked up helpdesk calls and user downtime. What was once a relatively simple problem to solve on the Server end are now a wild fires burning in a thousand locations.
One of the factors driving this is the myth that hardware (namely storage) is expensive. Hardware cost is actually one of the cheapest things in IT when you compare it to management and labor costs. Hardware can be even cheaper when IT organizations think out of the box and implement newer technologies and improvise and this applies to DAS (Direct Attached Storage) or iSCSI SAN (Storage Area Networks) solutions using commodity Serial ATA technologies. Mirrored Serial ATA hard disk storage costs a mere $625 per terabyte for the drives and the housing is inexpensive. With modern inexpensive backup solutions that also think out of the box, there is absolutely no reason not to deal with the email storage problem centrally.