You can thank intel for that. Crappy modems.
Why would he blame Intel? The WiFi SoC/chipset is provided by Murata in collaboration with Apple has it has for the past 2-3 years. Intel is providing the Cellular SoC/chipset and both chips are using the same antennas built into the frame of the phone. Murata is just a manufacturer producing chipset based on Broadcom design. Apple has been using Broadom design for like 5+ years now.
In regards to WiFi SoC/chipset Intel is actually on top of the game. Providing some of the best mobile and desktop 802.11ac SoC's/chipsets on the market. Intel and Qualcomm-Atheros are currently the two providing whats considered the best 802.1ac SoC/chipsets on the market.
When it comes to Cellular it seems like Qualcomm is battling at the top with Huawei, with Intel and Mediatek falling behind.