It did though? Trump pulled out of the deal in his first term and then Iran enriched from 3%.
If JCPOA was followed by both Iran and the US to the letter, we would face a similar crisis to the one seen today, except around 2031-2035.
What matters is ongoing engagement and monitoring, it's a far more tractable position than standoffs with zero knowledge or interaction.
Claiming "agreements are renegotiated and extended" is hypothetical. What incentive does Iran have to agree to enrichment caps post-2030? Why would Iran give up its strongest negotiating card, its nuclear program?
* Global sanctions relief
* $100-150 billion in frozen assets
* Access to the global oil market
Iran in 2030 under JCPOA already has access to all three. The US already played its best cards to get Iran to agree to JCPOA. The US has little new to offer, other than resumed sanctions.
And with JCPOA and its possible continuation, that was a joint agreement among a number of countries - in the current situation, it’s just the U.S./Israel (+ them trying to impose their will on other countries to go along with any carrots/sticks).
Not turning the country into a parking lot is a rather generous offer.
What's not hypothetical is that, under the deal, they agreed to not enrich until 2030. What's not hypothetical is that Trump abandoned the deal, with nothing to replace it, allowing them to start enriching in 2017 instead.
And if you're going to claim that renegotiation is hypothetical, then you also have to agree that any other possible future outcome, including one in which Iran develops a functional nuclear weapon, is also hypothetical.
And those 13 years would have been plenty of time to extend or renegotiate that agreement.