To replace a burger is much easier than to replace a steak. We'll probably need synthetic meat to do so, I can't see a perfect steak made from peas anytime soon.
You're not looking at the big picture.
Ground beef is what is the driver of the fast food industry, it's their main product, McDonalds ain't serving steaks. In the service industry, ground beef is over 60% of the beef sales. At home, ground beef is ~50% of total consumption of red meats.
You're looking at a ticking time bomb where the entire fast food industry will have a product that tastes like meat, chews like meat and eventually is as much or cheaper than real meat.
This is why when people scoff at the Impossible Burger having saying "no" to restaurants and instead going to Burger King for their limited production and demand, they are being beyond ignorant of how being first to the market with a meat substitute in an industry that will eventually take over animal born beef is a move that has incredible foresight.
Within the next 15 to 20 years,
at least half of all red meat demand can easily be from lab grown meat and plant based meat.
And that's a big thing to remember, we're not even talking about lab grown meat, lab grown could very well take the mantle for complex meat structures like a steak, which would be the death of the animal based meat industry.
I wouldn't be shocked that by 2050, animal based meat are a luxury item and average consumption of meat is either lab grown or plant based.
So yes, replacing ground meats is an inherently "easier" endeavor than a steak. That's not the point nor the target. Replacing ground beef is such a major step froward in terms of environmental impact. Agriculture is a smaller piece of the carbon pie, but it's one of the most complex and difficult slices to reduce when compared to transportation and energy production. The fact we have a clear path forward to reducing that slice of the carbon pie is something nobody thought was really possible ten years ago. This isn't taking into account the massive reduction in water usage as well if animal farming vanishes as a mass industry.