Plugins are accessory tools and utilities to make specific tasks easier/faster.
Many are created by users with a specific task or goal, The developers of Sigil Built in a way these could be attached to specific areas of Sigil.
My most heavily used one is
TagMechanic (mostly to despan unnecessary spans inherited from other conversions? like your span class="font6")
If the entire P needs a font, why not define .wfont6) <p class="wfont6"> ?? and stop requiring a second CSS lookup for those P (in many cases the span was redundant or the default: font-size:1em; or color:black;
