They were ubiquitous, it just didn't produce stalemates because armies didn't rely solely on artillery and human waves to break through.
They were still used because they still worked against poorly supported infantry.
Still are used, look at Ukraine.
Obviously the comment was mostly referring to WW1 but there were many battlefields that would have looked very much like their WW1 counterparts until some tanks or air support showed up.
There was very little trench warfare in WW2. Unless you're talking about the trenches for the death camps. Those were some really big wide trenches.
They were ubiquitous, it just didn't produce stalemates because armies didn't rely solely on artillery and human waves to break through.
They were still used because they still worked against poorly supported infantry.
Still are used, look at Ukraine.
Obviously the comment was mostly referring to WW1 but there were many battlefields that would have looked very much like their WW1 counterparts until some tanks or air support showed up.
On the bright side they didn't make any boomers.