Moss damages your shingles in three significant ways.
Moss on roof tiles damage.
However the greatest benefit of moss removal is on the gutters.
In addition the water trapped by the moss pools in gaps between your roof s tiles and as that water freezes and thaws it can pull the tiles apart causing even more damage.
Once moss is removed there are less blockages and your gutters work more efficiently.
First moss will strip away the protective oils on your shingles making them susceptible to erosion and sun damage.
Second moss absorbs water.
Ultimately moss growth on a roof can result in costly repairs and can also reduce the lifespan of your roof.
If you allow large patches of moss to grow on your roof these patches hold water against the surface of the roof which can cause the roofing materials to rot.
Moss alone cannot damage the tiles.
Moss on roof tiles can cause multiple problems such as wood rotting and the obstruction of drainage points.
Moss absorbs and retains water.
If you are to use a power washer you have to make sure you are standing on top of the roof and pointing the power washer downwards.
Without any protection your shingles will warp and crack in the sun significantly shortening their lifespan.