No, not really. At least not for the vast majority of people.
If we’re talking about 3D fabrication tables, with supporting ribs and sidewalls, the engineered block-style nature of the top already makes it about 30 times more rigid than even a 1” thick steel plate. So it’s not going to bend easily from what you’re doing on the top of it.
Additionally, it’s best practice not to even have the work material laying directly on the surface of the table. It’s best to use machined spacers to elevate the work above the table. It doesn’t affect flatness or accuracy, and it allows for downhill welds to not run into the table surface, and keeps the work exposed evenly to air so it can cool evenly and not act like it has a giant heat sink on one side and air on the other.
Having said that, if we’re talking about heavy industry manufacturing where you’re welding 2”+ thick plate all day long every day, you’re going to be using some of the biggest, heaviest tables made by companies like Bluco or Siegmund. In that case, you’d also have the heavy lifting equipment to deal with those big boy tables as well.