Pump group? Man! You have to be careful, I have friends who have lost a lot from such groups. Although, I don't know how legit this one is, you have to be careful. Is best you get insights yourself from any coin you wish to buy. Even Binance, Bitget and some other exchanges do give insights into coins that do well. You can start from there if you wish
The advice you say is completely logical and not wrong because basically everyone has to rely on their own knowledge regarding anything, including trading. The pump group can also play bad intentions and roles when they see that one of the participants has more money in it, so it would be wise for anyone not to rely on other people's thoughts in trading except based on their own thoughts on any coin on any exchange.