Basically a list is much more cleaner and it will make deleting stuff easier.
Example:
!delete {var.*} - This will not work, requires deletion through variable.csv now imagine if you have 1k variables
!delete {var::*} - This will work, no hastle! You may say, omg that's not gonna make any difference!
Now, what about your {freeze.%player%}, you're only setting them to true and false, now imagine the dozens of variables that will stay in your variable.csv. EHH, I'll just delete the variables in the variable.csv!
Do note that editing the file is very dangerous, it may corrupt your whole variable file What will happen if there's alot of variables?
It will result in the warning where your variables are gonna take awhile to save and if the server crashes it will result in some variables not saving.