No. Voters vote in primaries. Delegates get elected by voters at caucuses to represent the voters who elected them. Just like the Electoral College.
There is no "deemed necessary." No one deems anything. The elected delegates vote on rules for the convention. The rules provide a process to follow when no candidate comes to the convention having received 50% + 1 of the required number of delegates. That number is required by the rules - voted for by the elected delegates.
It's very similar to the process followed by the Electoral College and would be very similar to the process for an Article 5 Convention of States. You're not opposed to either of those, are you?
But here's the rub. The winner in Pennsylvania's April 26 primary won't be guaranteed all - or even most - of the state's delegates.
More than three-quarters of Pennsylvania's delegates are unbound, meaning they can choose which candidate to vote for at the convention. They're not legally required to vote for the state's primary winner.