Perhaps a feature such as a property named “Displayed text” under both textboxes and textlabels would fix the prevention of using richtext on input. it would greatly improve the feature usage on more than just bland non user generated texts.
this properly would basically be a read-only of the .Text property just without any html if richtext is enabled.
Until this is implemented (if ever) user generated content can be filtered from html with a simple line:
local NonHTML_Text = text:gsub("%b<>", "")
sadly this would take stuff like <hi I'm voided> in account so feel free to modify it to specific cases only