We did not get good advice out of ignorance when building our house and are currently building an Energy Saving Ordinance house with gas + solar thermal
I don't necessarily see it as bad advice. The general contractor builds his houses like that, so why not? It is mature and very economical technology. Without gimmicks and without exorbitant extra consumption, only if a sensor malfunctions or the flow temperature is set 1-2°C higher than necessary.
Among the negatives, only the fossil fuel is truly negative. Price fluctuations for electricity are significantly greater than for gas. With solar thermal, you have endless hot water from March to October and if you want, you can cover the rest of the roof with photovoltaics. The biggest advantage of a gas boiler is that it is economically viable compared to a heat pump of any kind without subsidies. With heat pumps (unless you do it yourself), it is not economically viable at all. The technology is great, no question, but it is simply sold to the end customer at too high a price.
And the horror stories about price increases and the evil gas are, as of today, not worth mentioning. Sure, we are getting the Greens into parliament now. Let's see what that brings. But as of today, the price increase for gas for a modern single-family house (no, not one from the last century) is only marginal. It looks much worse with the beloved car.