A serious graphic based game needs to be installed on a serious computer. This means:
a) you cannot play it from work in your lunch break if you cannot install it on your work desktop. You cannot play it from a library computer, etc, etc.
b) you cannot play it from your ipad/notepad.

On the other hand a mud per se does not need much in terms of either computing power or disk space, only an internet connection is required and this is much less of a constraint then it used to be.

The problem right now is that it is impossible at least for me to play CF competitively without a proper client with aliases, etc. Setting everything up perfectly requires both some basic programming skills and experience with CF.

However, it would be quite trivial to create a purely web-based application that would allow to play the game competitively without a client, especially with a few simple changes to the game itself:
1) allow you define aliases and buttons for the most command combat commands.
2) perhaps simplify information processing to eliminate tedious things without negatively affecting immersionor combat. For example:
- show you the things affecting you without having to type affect. (Having to type affect and then searching for the interesting part in 10 lines of text serves no point. Also it makes sense that you know what hurts/affects you without having to take any special action.)
- get rid of "where" spam. You could be alerted of somebody entering the area or being close based on some parameters or possibly with a short delay (which could also depend on the entrant for example a sneaking class could be noticed later).
- have your position show up in some diku like map
- and so on.

With changes like this one could play cf on an ipad while riding a train or in a lunch break at work. That is something graphic based games cannot compete with.