RADAR Video Signal and Matched Filtering
The simple answer is the matched filter increases the signal to noise ratio of the reflected return signal.

As the signal propagates from transmitter, the power that impinges on the target is proportional to $1/r_{target}^2$.  The reflected energy back to the transmitter is also proportional to $1/r^2$, so the received energy is proportional to $1/r^4$.

The received back echo power is very small and the matched filter maximizes the deflection of the echo with respect to the noise in the receiver.

This is a simple explanation. There are many types of RADAR, and there are additional ways to make the echo stand out with respect to the noise of the system and the clutter echos present in all real systems

Those additional ways that are specific to the different kinds of RADAR systems to make the echo discernible. There are various ways to modify a matched filter for a specific kind of applications but it would be hard to say they were alternative to a matched filter. The underlying optimality characteristic of a matched filter justifies few alternatives.