I dont think there are disadvantages. The only problem is designing of such circuits, which are more difficult due to interaction between the stages. In Integrated circuits, however, we have to use direct coupling, since the inclusion of large coupling capacitances in monolithic ICs is impossible.
The Directly Coupled Loop has its windings directly attached to an Amplifier. Usually the main Tank Coil (parallel tuned circuit that forms the loop primary) in the loop is grounded at the center of the winding (center tapped), to allow for electrical balancing. The Amplifiers are usually but not always J-FET’s, with 2 FET’s in a Differential configuration, where the ends of the tank winding go to each FET gate. The Transformer coupled version uses a link winding to couple the signal to the receiver. This version can be amplified or non amplified.
The physical size of the Loop Tank Coil affects the overall pickup (capture ability) of the loop. The larger the winding size the greater the pickup. Larger loops will also be easier to balance than smaller ones.