Altitude plays a large role in regulating plant species composition of a particular site. As one climbs a mountain different plants and habitat types appear and disappear. Some plants are adapted to grow throughout wide ranges in altitude, temperature, moisture, soil type, etc. Others hide in tiny niches.
Some niche plants only exist because it is hard for people to reach them. Air, water and heat pollution can still reach plants wherever they hide. So, congratulations! We won against nature for a short while! But wouldn’t losing have been more pleasant?