Neither party runs presidential primaries when their guy is incumbent. It’s almost superstitious, that having someone ‘primary’ your incumbent is going to make them lose (because of losses under those circumstances by Ford, Carter, and Bush Sr.
Of course the cause/effect is backwards, they were primaried because their administration was at risk, they weren’t at risk because of the primary, but as superstitions go…
But they are still running primaries? If talking about the presidential specifically, they did a typical primary in 2020 and sure in 2024 it was not done, but we’ve got people blaming “real primaries” against incumbents for losses in 76, 80, and 92 and neither party does it as a result.