Agreed, But brokers know if their retail customer accounts are losers or winners and such have an edge by fading the former and copying the later. They know that 90% of directional traders lose. This explains how all those fringe, small Futures brokers survive. It's not just from commissions.
I think that worrying about whether a broker is analysing your trades is a total waste of time. To make money from trading, you have to execute trades through a broker - or you can go and buy your own broking firm. So why worry about something you can't change. If you have a good system, you'll make money. If you don't, you won't make money. Focus on getting your system right.