Intel isn't ballasted so much by chip fabrication for phone handsets. TSMC is. The few years of stagnation in the client computing segment coincided with early delays in the 10nm transition. It's always easier to lay out big money for long-term projects when your business is strong, but that just wasn't the case for Intel around 2015 or so. Handsets were booming, as was parallelized GPU computing. TSMC was a natural beneficiary due to its customer base.