Of Mac laptop line 2011, three (of five) models contain SDIO controllers: A1278, A1286, A1369. 2012 models A1278 and A1286 do not contain a SDIO controller.
So, you are angry at Apple purely because some Macs from 2011 can optionally boot from their SD slots?
I've actually booted from SDXC cards in some 2011 or 2012 (the Sandy Bridge year) Macs that I've got and it works fine. I'm not switching to SDXC as my primary boot disk, but it was a handy way to build a utility boot disk at the time.
Do you know of ICBM (Intel chip based Macintosh) which boot from: APT (ATA Parallel Transport, a.k.a. PATA), USB MSC, IEEE 802.3, IEEE 802.11, IEEE 1394 SBP, and Thunderbolt UTDM?
Apple Mac firmware has awareness of SDIO/SDHC (this instance of SDHC refers to ShitDigital Host Controller, not ShitDigital 32-bit * 512-octet), at least enough to boot from conventional SD cards.