You can't believe everything you hear, and some of the things you hear are out of context.  So I pass this to you as an interesting statement, said to be from a manager at First:

"We can't market our local trains because they're too crowded already".  Yes, there's probably a grain of truth in that - although I think that they DO have services, and upcoming services such as the 06:19 Swindon to Westbury and the 19:35 Westbury to Swindon, which will have capacity.   I have asked about the market and marketing of these services - half of the trains left on the line - but the answer I got referred to them running at that time of day because that's the time that the train can be made available and it really didn't touch on my question, which was looking forward to (I hoped) a customer base and a useful and used service.