I think when people say two years they do not necessarily mean two years in their entirety.
However, there was certainly one full year of disruption, from March 2020 to March/April 2021.
I am someone who likes the great outdoors. I love a nature walk, love the sea and lakes and the rivers and ponds. But with the best will in the world you cannot run around a wood all day long.
There are countless factors at play when it comes to speech acquisition. Children need to watch lips move, observe facial expressions, have chances to observe reciprocal speech interaction - screens can never replace that and a child won't learn language from a screen. It’s something that relies upon a variety of human interactions.
Some posters are insistent that it’s poor parenting causing the problems linked to in that news article. In a way, I’ve no excuse as I only have one baby, but I also have a DH WFH so I couldn’t really spend all lockdown chatting and singing to that baby. And certainly nobody who is WFH with other kids would be able to do that.
Then you take away the groups (and we know they didn’t have them circa 1940s, but take a look at outcomes for children then) the shopping trips, the visits to family, the library, the museum, and you replace that with one walk a day then back home, like the start of lockdown. Even the best parenting is not going to replace the myriad of social interactions.
Children also need to practice using speech on non family members - was anyone else encouraged to give the lady in the shop the money and say thank you? And handling cash … why else might that be a problem?