Under EU law, the rights flow from the law itself and not from the possession of documentary proof. If the requirements of the law cease to be met, the status is at an end, even if you have documentary proof of having held it at some time in the past.
The card is only indicative of the status you hold on the day the card is issued. If the circumstances under which the card is issued change, then your status under EU law would change even if you held a physical card.
As an example, if a durable partnership between an EEA citizen and a non-EEA citizen broke up before the non-EEA citizen acquired PR, then the non-EEA citizen's right to reside comes to an end even if s/he continues to hold a card.
Also see
EEA Regulations 15 & 19.
15 (3) The right of permanent residence under this regulation is lost through absence from the United Kingdom for a period exceeding two years.
19 (4) A document certifying permanent residence and a permanent residence card is—
(a) proof that the holder had a right to reside under regulation 15 on the date of issue;
(b) no longer valid if the holder ceases to have a right of permanent residence under regulation 15;
(c) invalid if the holder never had a right of permanent residence under regulation 15.
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.