Back in 2008 with little knowledge of how to look after my violas I used to leave the plants untended during the winter ,and wait until the spring before cutting out the dead stalks, stems, of the previous year’s growth.
This old growth might protect the new growth emerging from the centre, but can harbour problems.
This however is how the plant in its natural state would survive and perhaps only the strongest would remain.
The much larger hybrid Florist types , grown mainly for shows ,are much weaker than these violas and violettas, especially the pansies Show and Fancy Types.
The violas have multiple stems, but the majority of Florists Fancy Pansy and some show types have only one main stem in the majority of cases hence the greater chance of perennial growth.
The exhibition Violas are more like the bedding types ,but with much larger flowers and can make garden plants which will live year in year out.