No matter how faster spawns, if the feat is “complete the weekly mission 12 times” that's means 3 months to complete the feat….or spend a lot of money…
From that perspective, of course. However, if you have kept up a membership and saved some of the replay badge perk, you could reset the mission without issue if you chose to; if you have enough replay badges saved up you could just reset it 12 times and be done with it. I'm not suggesting that players who have enough replay badges should do this, but it is an option.
True, but it is an option. I have a membership, but I choose to not use my replay badges to reset; it's an option open to me. So, every week I will get 3 large loot boxes instead of two until this feat is done; seems like a win to me. I don't mind that this feat takes a while to complete. By the time I finish this feat, the next episode should be on the horizon as well as the next seasonal event. There are always options to getting feats done; it's your decision to decide which one(s) you can and will use.