I think many players got permanent kits in the clan at the beginning of combat or random geniuses reasoning about the correct behavior on the battlefield. In case of closing arguments, the people from the latter category fall to insults. To read them is extremely unpleasant, and many of the strong expressions Mat filter is not able to weed out.

To reduce the flow of unnecessary information created mod custom filter chat for World of tanks 0.9.14.
You will be able to hide the messages from alive/dead players, add stop words (phrases with these words will fall under the filter), hide multiple identical messages in a row, disable the filter in company battles or training, and change many other options.

Add the desired settings in the file.
WOT\res_mods\0.9.x\scripts\client\gui\mods\mod_battlechat_filter.json
Use the Notepad++