Countering Plague is not as simple as “don’t cleanse.” Unless your entire squad are god-like loopers who can play the whole game injured without going down, you should absolutely cleanse against Plague. Some of my easiest Plague games have been against teams that don’t cleanse. Just know where and when to do it.
Try to cleanse at fountains on the edges of the map or in areas where gens are already done. You want to make Plague have to go out of her way to get her power (swamp is brutal against Plague because her fountains can spawn on the very edge of the map). Don’t cleanse if there’s a high risk you’ll be infected again right away (ie. stop cleansing before unhooking your fully infected teammate). And if you’re entire team is cleansing back-to-back, you should too, as fast as possible. If you have a chance to force Plague’s power onto her, you should. Not only are you denying her more potential uses of her power, but you’re likely forcing onto her at an inopportune time.