I never expected I’d see these two companies in the same sentence! But I guess you are right, it’s quite a world we live in - full of disruptors. 
@Vlad and @Rob14 did a stellar job explaining how our exchange rates work and how they align with our customers’ needs.
I’d be also surprised if II used the interbank rate (can everybody please link source when they make such claims), but if they do, you get a fantastic 0.25% if you buy £600,000 worth of stocks:
Now, if that’s the dimension you look at, my friend, more power to you. II could be a fantastic product for your needs! And to be sure, I think some traditional brokers e.g. HL, fintechs e.g. Revolut and a lot of other companies built great products for their audience, but they are not all things for all people, and neither is Freetrade.
Makes sense?