Not necessarily true. SoCalMotoGear.com has drop in bulb replacements that work quite well and after a year in service have not had any troubles at all.
Turn signals will require a change in the flasher relay which is a little bit of a PIA to perform....but not impossible. And I would steer clear of SoCal's license plate bulb replacement....I've had troubles with those failing. HOWEVER, Sylvania now makes an LED equivalent of that bulb which works very well and can (at least hereabouts) be had from any Auto Parts retailer in town.
.....sT