Myself I "grew up" in an X11 and Sun "the network is the computer" world. Have not used Citrix more than an hour, but my interpretation was that Citrix made a (huge) business out of Microsoft completely missing the network in the 90s. Both LAN and Internet. So yeah, they allow you to access a Windows computer over the net. Windows still exists so the business continues.

For Tibco I have no equivalent story to tell.

Edit: https://en.m.wikipedia.org/wiki/TIBCO_Software gives an idea.