harry potter - Does it break a rule for a first year to play Quidditch for his/her house team, or is it simply tradition?

Is it against the Hogwarts rules for a first year to play Quidditch, or is it simply an unspoken tradition that first years never make their house team?

‘You’re joking.’ [Ron said] It was dinner time. Harry had just finished telling Ron what had happened when he’d left the grounds with Professor McGonagall. Ron had a piece of steak-and-kidney pie halfway to his mouth, but he’d forgotten all about it.

‘Seeker?’ he said. ‘But first-years never – you must be the youngest house player in about –’

‘– a century,’ said Harry, shovelling pie into his mouth. He felt particularly hungry after the excitement of the afternoon. ‘Wood told me.’

_{Philosopher's Stone - page 113 - Bloomsbury - chapter 9, The Midnight Duel}

Oliver Wood told Harry that Harry was the youngest Quidditch player (at Hogwarts, I presume; not necessarily nationally) in a century; however, Wood didn't mention whether the previous youngest player was a first year, like Harry is, or if the previous youngest player was younger than Harry -- say 10-years-old -- or older, like a 12-year-old second year. I know we have no way of knowing who the last youngest player was before Harry, but has J.K. Rowling addressed anywhere whether first years are not allowed to play for their house teams, or if it's just kind of an unspoken rule that it doesn't happen?

For what it's worth, I don't think McGonagall getting special permission to get Harry a broom is a definitive statement on whether the Quidditch thing is either a rule or a tradition; first years are not allowed to have their own broomsticks at Hogwarts, we know this. But there are school brooms students can use.

★ A canon-based answer would be great -- books, J.K. Rowling interviews, Pottermore, etc.

Answer

I just came across the following in The Half Blood Prince, Chapter 11: Hermione's Helping Hand:

As Harry had expected, the [Gryffindor Quidditch team] trials took most of the morning. Half of Gryffindor house seemed to have turned up, from first years who were nervously clutching a selection of the dreadful old school brooms, to seventh years who towered over the rest, looking coolly intimidating.

Harry doesn't tell the first years to leave, but lets them try out "and it could not have been plainer that they had hardly ever flown before."

So it looks like it's just fine by the rules for a first year to play on the Quidditch team using, as you suggested, school brooms. It's just that it's a bit rare for a first year to be any good.