I think this is half the solution definitely... However, there are tonnes of bots with high level cards too, we have kicked out a few bots from our guild that were in diamond 1 to champion 2!!!
There're some things that could be done quite easily that would allow us to limit the number of bots to stop the economy from crashing...
#1. IP Limiter = say 2 accounts per IP (this is already done by lots of games that are monetary based such as online poker etc.)
#2. Number of game watcher (if a user plays more than say x amount of games then it could flag the account for members of the team to moderate)
#3. Simple username checker (for example we have bots simply using 1, 2, 3, etc on the end of their name) hbk1, hbk2, hbk3, etc. Again, flag for manual action.
#4. Heat map checker (like used on websites to track where the user is looking, where they are clicking etc.) This could be used to easily identify bots as they will always click the same place with little natural movement.
#5. Recaptcha (no not the am I human one) the invisible one that you don't need to do anything with.... It's actually pretty good and will limit those bots down...
#6. Block users who post with blank referrer agent... simple trick used by websites and will limit bots.
#7. Track down the Telegram bot owners, join it, get the code, implement a script to stop that script working....
If we're still getting botted after this then I'd suggest a honeypot trap.
Honestly, with that lot implemented then I honestly believe you'll reduce bots by about 80%+ and in no way does it alter the game to the real users.
Hope this helps,
Peace!