yep, for such cheap prices many would turn up just on a whim if they have nothing better to do. i certainly would if i were local.
on the live coverage they said it was something to do with having enough ticket staff to ensure the NFC stuff works correctly for people... bit strange of a reason really.
I actually wouldn't be surprised if the club did some sums and quietly capped the attendance to keep the night the most cost-effective version it could be, based on what I saw of the ticketing.
To begin with, the club only sold lower tier Kop and lower tier Main, and once those tickets were pretty much gone they opened up lower Anfield Rd. These blocks were pretty much sold out for over a fortnight unless a person wanted a single seat, but it wasn't until a few days before the sale cut-off that they opened up the 300 blocks in the Kop. I had a ticket in 105 but got directed to the turnstiles for the 200 blocks, and everyone queuing for those had paper tickets despite the club saying repeatedly that the match was digital ticket only. Those paper tickets were obvious freebies. I already knew the club was handing them out locally, and figured they would be for the 200 blocks to explain why the 100s and 300s were on sale but not those between. Unless someone here can tell me they bought tickets for the Dalglish stand via the club, then everyone in that stand was also on freebie tickets because at no point was that stand on general sale.
Between the blocks available to buy in and the freebies, that fills up the entire lower tier on three sides + a full Kop. To have sold any more tickets would have meant opening up the higher tiers, which probably would have added a fair whack to the expense of using the stadium. Presumably the club felt it wouldn't be able to sell enough additional tickets on top of all the ones sold and given away filling the sections that were filled to justify opening any more. Ending sales two days early in that scenario isn't such a big question mark because the match was effectively 'sold out' anyway.