And there are other data centres use a mix of SFP+ and 10GbaseT (as in the ones I work at). If this weren't true, then you wouldn't be able to buy 10GbaseT switches from all the major vendors.
Interesting. 10GBase-T modules eat power and produce a ton of heat due to how hard the transceivers have to work to get those frequencies down twisted pairs. For short range SFP+ and DACs rule, for anything longer in the DC optical SFPs is usually how they roll.
10GBase-T is expensive to purchase, expensive to run and has limited range. A 5 meter DAC is less than £15 and uses less than half a watt and you're done, 300 meter range MMF optics come in at £15 each side and consume 0.6 watts each. 10GBase-T costs 3-4 times as much each depending on the range you're after and uses 3-5 times as much power.
To each their own. I haven't seen it used much in any scenario. All SFP+/SFP28/QSFP28, DACs for short range, optical longer, and boring gigabit copper ports from top of rack switches to servers. If you scored a good deal on switches with incorporated 10GBase-T ports all power to you guys. Super situational.
Fin