I truly don't think anyone was trying to be rude (and there have been times I've thought members have gone a bit far, but I didn't think this was one), simply offer information and advise that might be helpful to you in this. If you want to breed quality chins, then knowing things like, for instance, why it can be best not to pair mutation to mutation, especially at first, and understanding the placing system at shows so you know that while a first is good, there are higher awards, is just useful, right? They've mentioned mistakes they themselves made, to help you avoid them.
I'm sure your experience with dogs has given you an idea of the responsibilities of breeding, and members are taking that into account, but of course, as you know, not all of that experience will transfer to chinchillas. Since you mentioned you wouldn't have been able to achieve the quality you did in dogs had you not been responsible, you've probably seen for yourself that, sadly, show success actually doesn't necessarily prove a breeder is responsible, I'm sure you're aware of the controversy over health problems in pedigree dogs, sometimes directly caused by breeding for what the interpretation of the breed standards suggested was show quality. Please don't take this as criticism as I am not suggesting this was the case, I have no reason to think that. It's just your experience with dogs doesn't tell us what you know so far about chins, other than, very importantly, you do know breeding is hard work and can be heartbreaking.
When you're able to attend shows, you'll get a better idea of how everything works, how to judge quality and about breeding for different mutations (ebonies particularly in your case), and be able to look at where you are with your own chins. Hope it will be interesting and helpful for you, I know I've certainly learnt a lot from going to shows and listening to the judge's comments. You do have time to continue to learn, I think people were just concerned that you bought two chins you intend to use as breeding animals relatively quickly, and without being able to attend a show to get a bit more experience first.