In my opinion, providing slippers for guests is not necessary. If people know the home is shoes-off, they can bring their own slippers and if they have not visited before it is hardly a great endurance to be in socks or bare feet.
Some people insist that providing slippers is a must by pointing out the example of Japan:
In Japan, you are not expected to go bare foot; the host will always give you slippers.
This is actually an half-truth. It is true that hosts will normally provide slippers in Japanese homes. However, these are intended to be worn in the hallway and kitchen. Bedrooms and living rooms normally have tatami (grass mat) flooring. It is expected that one removes slippers and step on the tatami in either stocking or bare feet.
Carpet has become more common in Japan and often it is expected that one removes slippers even before stepping into carpeted rooms.