Yeah, with that style of cone (which can’t fit in the pot), one of the main reasons for the Ziploc (or a Caddy) is to protect the cone.
BUT, I actually have found it useful. I’ve got an 850ml pot. I boil up enough water for both dinner and hot beverage at one time. Water for dinner goes into the Ziploc with cozy where it steeps for a while for full hydration. The pot is mug shaped and becomes my tea/coffee/hot chocolate cup. Works out pretty well, and it’s a bit more efficient to boil everything at once rather than doing separate boils.




