I believe what is being missed here in there are implied rules and agreements already in place in healthy relationships.
For newer couples or people that are not yet a couple, having these conversations around consent is vital for building trust, intimacy, and respecting boundaries.
For established couples, some things can be an entire conversation without an actual word being said, specifically because they’ve put in the time and work to lay those roads of understanding and listening. For instance, maybe your SO has a different wardrobe for intimate occasions as opposed to their regular cozy sleepwear. If they are wearing regular cozy sleepwear the implication would be that there is not an inherent green light on more intimacy in that moment.
Also, on a side note consent can be still be something flirty/sexy but how it’s done matters too. I feel many people who have had their boundaries trampled or ignored are going to need more active reassurance and checking-in.