I saw a 3D printed automobile at a trade show last summer.
Full size, fully functional, drive it away, not a scaled toy or model.
And I have a long-time friend who works at a company that makes equipment capable of printing things nearly that big in a single piece using laser-fused metal powder.
So...... yes, sort of.
There are a few "gotchas".
First of all, the printed segments were the diameter of small rope (must have been one heck of a large nozzle, like maybe a 12mm orifice).
Second, even so it was still printed in parts and bonded together.
Third, if you print something like a typical Eiffel Tower model all in one pass on an FT-5 (say 14" tall) it probably contains as many or more actual printed segments as the automobile did, believe it or not.
I understand that you are thinking of a 4 foot cube volume.
The main limitation for printers of the class of the FT-5 and similar is probably not so much a mechanical one as a data one.
The data files (.stl or .gcode) would become monumentally huge.
It is very doubtful that the microcontrollers and firmware that drive our printers could deal with them.
Maybe, but I wouldn't bet on it.
More likely a much more powerful computer would be required.
And if you just use the FT-5's board as a slave to a PC or Mac, then you would be dealing with data integrity and sustained data links for perhaps weeks.
Secondly, the larger you make the frame the more thermal expansion and flexure would become issues.
You probably couldn't keep layers aligned very well unless the structure was improved quite a bit.
And you'd probably have to resort to closed loop servo motor drives with glass scales or other sophisticated measurement methods.
Also, the strength, stiffness and weight of mechanical components do not, unfortunately, scale linearly with size.
So even moving the gantries and other components around would become a problem.
And they don't make 1.75mm or 2mm filament in 250kg rolls that I am aware of......
So unless you want to feed from pellet hoppers through direct extruders (as the car printer did), that is a major issue.
But it is an interesting thought experiment.