Because feedback is irrelevant.
If you have a problem with slow delivery, use the Resolution Centre to get a refund.
The eBay Money Back Guarantee allows you to open a Dispute for the 30 days following delivery or estimated last date for delivery.
If the seller cannot prove delivery (not shipping delivery) you will be refunded.
If you allowed that window to close, Paypal allows 180 days from Payment for disputes.
If the seller cannot prove delivery (not shipping delivery) you will be refunded.
And of course, you can also try the chargeback policy of the credit card you back your PP account with. Card policies differ.
But feedback is not used by eBay to assess member accounts and most buyers believe a 95% FB rating is excellent.