Variety Leads To Incompatibility, Not Spice
From a user's perspective, one of the biggest problems with the number of IM programs is the difficulties inherent in making all of them interoperable. Because all the big vendors have created their own unique protocols, even their efforts to make them work together limit the resulting functionality between them. This means that depending on which pair (or collection) of IM programs may be at work, users may encounter difficulties when exercising certain program features, such as transferring files between parties to a conversation. In practice, this means that people who want to interact with a large number of other communications partners must register for multiple IM networks, each of which requires its own set of software and tools. Then, too, it's important to consider the user agreements associated with each IM service, each of which is subject to its own distinct nuances and quirks.
Multi-protocol Messenger Programs
To avoid installing multiple IM clients you can instead turn to a multi-protocol client such as Trillian, Miranda, or Pidgin. The advantage of these programs is that they reduce the consumption of system resources compared to running several dedicated IM clients, and they also aggregate all contact information inside a single interface. Even these all-purpose tools, though, remain vulnerable to problems when it comes to calling on functions specific to one IM service or another, such as video-based communications. Frequent changes to the underlying IM protocols and clients also means that multi-protocol IM clients users must wait for their programs to catch up with changes to the actual source software. All too frequently, this prevents them from accessing those networks until their program is re-synched with whatever IM environment has been updated most recently.