the mechanic recomended to replace the orifice tube, accumulator and condenser for the following reasons. (1) when the compressor fails, it normally breaks down internally therefore all the "debri" that broke will end up in your system. The orifice tube is the first thing to clog up. If you dont change the orifice tube, your new compressor will have a high head pressure causing premature failure. (2) The accumulator has to be changed because this stores excess oil in the system, and will collect all the "debri" from the failed compressor. Also, the accumulator has dessicant that dries out moisture in the system. Reusing the old accumulator or "saturated" accumulator is like using a wet rag to dry a spill compared to a dry rag to clean up a spill. (3) The condenser can be reused but if you can afford it, change it. The condeser consist of small tubing to change the High pressure gases (freon gas) to High pressure liquid (liquid freon)........again "debri" can clog these tubings. Just like your radiator, when the tubings can clog and create a poor cooling system. In your a/c, when the condeser clogs up, it can cause high pressure in the system causing costly and pre-mature failures.
Also, most compressor manufacturers/ retailers WILL NOT guarantee the compressor if you do not change the orifice tube, accumulator and oil.
I hope this helps