No. Section 75 applies only to actions of the direct recipient of the CC payment, NOT to any 2nd or 3rd party.
If you book through an agent and the flight is delayed and you would be entitled to compensation after so many hours you would not get it if booked via an agent.
Same with holiday hotel bookings etc where you book through and agent and the room is not available. If you book directly with the hotel you are covered.
Also note you must pay at least £100 of any bill which is greater than £100, no matter the final full amount, on the credit card to be covered (UK rules). So if the bill is £1,000 as long as you pay at least £100 by CC you are covered. How you pay the balance is irrelevant.
Anything below £100 id covered if the whole balance is paid by CC.
Problems with goods and services: section 75 and chargeback – Financial Ombudsman service