MJ covers it very well but it is worth re-emphasising some points as a lot of (especially new) pilots seem confused.
I hold a PPL(A) on an EASA licence
NO - You don't.
You hold an EASA PPL on which there are Ratings.
Although it needs a valid Medical to be used, The Licence does not expire. The Ratings (that you have mentioned) do.
When you pass a Medical exam you have
met the requirements to be issued a with Medical Certificate. But you do not actually have a valid Medical until you have been given the signed piece of paper.
When you applied for your PPL you had
met the requirements to be issued with a Licence but you did not have a PPL until you had received the piece of paper and signed it yourself.
Rating Revalidation is the same:
For SEP(Land) there are two methods of
meeting the requirements:
a) Passing a Proficiency Check with an Examiner
or
b) Having the required experience (as you correctly stated)
Once the requirements are met, that entitle you to Revalidate, you still need to actually Revalidate (in this case get an Examiner to complete the entry in the Ratings section of your Licence)
No Examiner entry = No Revalidation