>>539265920
Yes and no in my opinion. In the past with 3rd and 4th gen planes you could get away with it since fully developing a frontline fighter jet was still feasible by yourself even if you weren't the USA or Russia so your industry could still retain the necessary knowledge and expertise.
Nowadays we're already at the point where we're developing 6th gen fighters which outside of the US and China I don't think anyone can develop and build by themselves simply due to the monetary requirements. Within GCAP as much as we're going to share there are parts of the development that are going to be led mostly by a single country so your industry won't get the same "exercise" as it would've if you had developed it alone. Trainers could be the one thing where you can still fully develop them alone, letting your engineers pay for their bills and stretch their legs.
If your country is too small/poor you have no choice either way so it's a non issue, but bigger countries should take the risk and make their own stuff.
The issue with the UK is literally that they just started too late due to the 2006 decision to not enter the AEJPT but put all their eggs in the T2/128 basket to save some jobs.
But not everything is lost, while the Aeralis proposal is facing an uphill battle due to their modular design idea, it could also be their ace in the hole if they prove they can actually develop it. If they make a fully drone/autonomous variant it could serve as the platform for the loyal adjunct (in the low version) in the GCAP program. They could stretch out their decision by continuing to send their pilots here in Sardinia on the M-346 and allow Aeralis to fully flesh out their stuff.