Looking at this further, I note that the instructions link directly to the “mapping as a node” section of the wiki. It would be possible to follow that link and not notice the previous section on “mapping as an area”. That could be confusing if the station is already mapped as an area (which was the case in the first two examples I checked in my local area).
More generally, I don’t know how complete the instructions should be and whether they should be understandable to an inexperienced mapper - I don’t use MapRoulette normally so I am not sure what the expectations are.
For example I found this station near me mapped as both a node an area.
Node: Cártama (7567516148) | OpenStreetMap is a node named “Cártama”, tagged with operator and wikidata, and part of a stop area relation.
Way: Estación de Cártama (215235210) | OpenStreetMap is an area named “Estación de Cártama”, without operator and wikidata tags, and not part of any relation.
To avoid losing any information a mapper would need to think carefully about how to combine the two. Simply deleting the area would lose information about the extent of the station. Transferring the tags from the node to the area and deleting the area might be better, but the mapper would need to take care to add the area into the stop area relation, and would have to decide which name is correct. All of this seems to require a reasonable amount of familiarity with railway station mapping (including the whole wiki page, not just one diagram).
And this is for just about the simplest possible station. For a more complex example, with 4 railway=station objects, one of which is mixed with a train station building, see Node: Antequera AV (6572847598) | OpenStreetMap. Full confession: I have actually known about this one for a while, and even mentioned it on Mastodon. but before tackling it I was waiting for a conclusion to the 90-post thread on station mapping at Railway=station as an area?. Then I forgot about it!