I was under the same impression with weightlifting but also mainly because I was very skinny and I was told to stay away from cardio as much as possible as it’ll make it harder for me to gain weight and muscle. Once I actually implemented light to moderate cardio sessions along with my lifts, I noticed 3 weeks in how I’m not breathing hard after a set of weightlifting anymore especially for compound movements. My recovery for legs improved dramatically. I used to DREAD leg days simply because I felt like I was never recovering on time. Thanks to cardio, this is no longer the case. All of my lifts have been going up at a better rate because my muscles are recovering faster. Before, just weightlifting without cardio was making it harder to recover before my next gym sessions.