While they aren't directly to blame, note the emphasis in that first line: "particularly in the winter", this is because solar output is lower in the winter as are wind patterns.
Also, describing wind (solar truly is a very small segment) of the Texas electricity supply as "just a fraction" is misleading. In terms of installed capacity, Texas has north of 28,000MW of wind, making it the 2nd largest source in the state. And before I get called a liar on that again (happened in another thread), here's a PDF from ERCOT that shows installed capacity for various sources:
While that sheet references exclusively installed capacity (~25,000MW), there is significant wind that's been grid connected but not yet recognized as installed capacity. It IS however factored into the charts ERCOT produces for supply, capacity factor...etc. This bumps overall capacity to north of 28,000MW, or roughly 28%. That's reflected in this chart:
However, the blame still falls on the inability for gas gen to do its job to step-in for absent wind capacity as well as primary capacity, but I don't think it fair to ignore that wind's contribution to the event wasn't significant simply because it wasn't expected to show up at anywhere near nameplate in the first place.
This report covers why that is the case:
ERCOT only plans on, during the winter demand peak, there being 963MW of wind and solar capacity.
If you go to the 2nd tab, the top table shows average CF for the three different wind areas, which gives a total average anticipated capacity of 6,142MW
This report explains why:
News releases published by ERCOT.
It is typical for cold snaps and heat waves to be accompanied by periods of low wind. This is perfectly normal, which is why planned available wind capacity is so low. But it does highlight an issue with expecting meaningful contribution from wind during high demand periods. The bottom line is that Utilities don't. They plan on using other capacity.
That presents a serious issue if the plan is deep decarbonization with a further reliance on electricity as we push for electrification.