User blog comment:Lol is 4 Lollipop/What is the most useless plant?/@comment-5209947-20130505202547/@comment-26531060-20130506031355

To move zombies from a weakened lane to a more powerful lane. And to lessen the number of plants and sun required because:

RP RP RP RP - - - - -

RP RP RP RP - - - - -

acts nearly identical to

- - - - - - - G G

RP RP RP RP - - - - -

and the second format costs less sun and time.