Agreed, but I think there is a difference between the top six and the big six. The "big six" have become a definable group, if one of them finished outside the top six in a given year it wouldn't change peoples perceptions.
It's a given that there are "top" clubs and that bigger clubs will look to form alliances with each other to protect their interests and limit competition. My bone though is the criteria for inclusion. Spurs were included long before they reached the UCL final, is that based solely on commercial factors? Were they invited to join the big six or did they lobby for inclusion? Utd, Liverpool, etc must have given the green light. If they finished outside the top six for two seasons running, what happens then? Do they or any other club leave the group? Clearly not, for the most obvious reason that that scenario isn't likely to happen anyway, or if it is, as you suggest, they look to close off competition further.
There is no law against forming alliances and groups, but it takes a different turn when the 14 other clubs are asked to leave the room at a point in Premier League meetings.
You can argue we have been limited commercially by our dreadful on-pitch results and performances spanning into a 2nd generation but these proposals just represent a takeover of the league by that group. It's critical for us to be at the top table on and off the field or we will be confined to also-ran status for perpetuity.