All I needed to have running was a single application on my system or mobile for that matter. But today I need to have multiple clients with multiple versions in order to access all the IM networks I want to access.
Google scraped gTalk in order to make the move to proprietary Hangouts platform. Microsoft moved from a used MSN protocol (which had been reverse engineered well enough by then), so that they could force users to move to Skype. By now both ICQ and AOL are as good as dead (don't know if they are still around). The only one who has worked forward (according to me) is Facebook, they have based basic parts of their IM on Jabber.
To me that seems to be a step backwards. I have no problem of using a specific client when I want to more advanced stuff like, a Voice/Video call, share desktop, etc. But I want to be able to use text IM just from a single lite weight client.