1. It is very close to Athens (most of the way there is motorway)

2. It only has two (practically one) drag lifts, but it brings you to a mountaintop with a pretty hairy and long red slope, and limitless tree-level off-piste possibilities

3. It is beautiful, full of really impressive fir trees, and so is the way there.

4. It is dead cheap to rent skis and buy the lift card, at 10Eur each.

5. Even when it's crowded, most people are there for the snowball fights and sleighing with their kids, rather than skiing

6. It has a dedicated sleigh slope; safe for skiers and careful parents.

7. Nearby villages, mainly Levidi, have good accommodation options. While maintaining a village atmosphere and far from a luxurious, expensive resort

All in all, Mainalo is great for a day trip or a weekend from Athens if you are too experienced to even find Parnassos ski center limited and crowded, or if you don't like overwhelming Mykonos-like atmosphere: full of public health hazardous skiers!