A proponent is 'one who does something'. Or it can be 'one who promotes something - propels it forward.
A carpenter is a proponent of carpentry
An architect is a proponent of architecture
An activist is a proponent of activism
From the Latin proponere 'to put forward'
The word is usually described in dictionaries as someone who 'puts forward an argument' but it means more than that - it can mean to 'push forward' an industry, activity, way of being, thought, or art form - which is often done through action, and activity, not merely by talking.
If you want to 'be a proponent of eco architecture' for example, you could simply be talking about it, but another way of being a proponent would be to actually build an eco village that people can visit.
- Dickens - was a proponent of social reform (through his books)
- Madonna - is a proponent of women's sexual freedom (through her mode of dress, behaviour and way of being etc)
- Starbucks - is a proponent of great coffee