Landlord stuck in the 1970's (really old plugs)
Over time the molded plastic that receptacles, plugs, and light switches is made out of can become brittle and crack .
The components of your electrical system have a finite lifespan. When you see signs like this, it’s a good idea to replace as many of the old switches and plugs at one time as practical.
By combining multiple items in one service call can be a real cost saver.