I would say "Yes, absolutely"
We all want to learn and we want to learn from the best. Many of the world's greatest paintings are available as paint by numbers - so just think what you can learn.
Firstly, the scale and number of different colours used.
Secondly, typically (especially with landscapes) you can see the variety of colours used by the artist - and realise how they have built their palette.
Then, you are learning about colour placement, about size of blocks, strokes etc.
Of course, you learn about composition.
If the colours excite you, try making them yourself - and learn colour theory and the complexity of building the appropriate colour for each place.
In the end you probably have some colours left over - so you can expand and start your own painting based on those colours.
So, what's not to like? Have a go...