Usernames are online identifiers:
A non-exhaustive list is included in Recital 30
An individual’s social media ‘handle’ or username, which may seem anonymous or nonsensical, is still sufficient to identify them as it uniquely identifies that individual. The username is personal data if it distinguishes one individual from another regardless of whether it is possible to link the ‘online’ identity with a ‘real world’ named individual.
The data subjects are identifiable if they can be directly or indirectly identified, especially by reference to an identifier such as a name, an identification number, location data, an online identifier or one of several special characteristics
By definition commenting reddit users are covered, even if they haven't posted anything otherwise identifying -- but most have either way.
If a user is commenting they have an online identifier and are thus covered. If a user has ever referenced their relationship status, location or any physical descriptor they are covered. The GDPR -- it applies.
You're all over this thread saying this, what exactly do you think "right to erasure" means?
From gdpr.info:
Since the definition includes “any information,” one must assume that the term “personal data” should be as broadly interpreted as possible.
Here's a short list of information thought not to be personal which has later been found personal:
The idea that redditors do not have personal information lingering in their comments is absurd, GDPR 100% applies.
How exactly do you trivially remove all references to the physical, physiological, genetic, mental, economic, cultural or social identity of the person posting?
This is the bar you'd have to clear to ensure someone's comment history were anonymized per GDPR, miss a single one of these factors and your anonymous data is now reversible and thus infringing.