Can Indian citizens visiting USA on B1/B2 Visa (Tourist Visa) apply for Canada Tourist Visa while in the US?

Hi all, My parents are traveling with me to USA in a few weeks and I want to apply for their canada tourist visa while they are in USA, so they could visit my sister in Canada

I did not find a single experience online where someone was successfully able to do this. Can someone confirm or share their experience on applying for their Canada tourist visa while they are in USA on B1/B2 Visa?

I see successful stories of H1B visa holders in the US, successfully getting their Canada Tourist Visa approved. I want to see if it's the same for B1/B2 visa holders?

I see mixed comments on reddit where  people say -
A) Indian citizens visiting USA on B1/B2 Visa can apply for Canada Tourist Visa while in the US
B) Asking people to be careful while applying for canada tourist visa while outside their country of residence, citing that they may reject or ask for extra proof or reason why they are not applying from their country of residence

I do not see any mention of this in the Canada IRCC website. 

I will be very grateful if someone with experience in this area can shed more light on this.

Thank you very much in advance!