Why is declared that $0 le theta le pi$ for Qiskit's U3 gate?

Question

It stated in Qiskit's documentation.
This question arose after I accidentally called the U3 gate with parameter $theta$=$2pi$ in the program and Qiskit executed the program without error:
tetha = 2 * np.pi
qc.u3(theta, phi, lam, reg)

I checked other values out of bounds and every time it worked (including looping at a distance of $4pi$) according to the formula for U from the documentation (judging by the resulting unitary operator) but ignoring violation of declared boundaries for $theta$, e.g:
print(Operator(U3Gate(1.5 * np.pi, 0, 0)))
print(Operator(U3Gate(5.5 * np.pi, 0, 0)))
print(Operator(U3Gate(-.5 * np.pi, 0, 0)))
print(Operator(U3Gate(3.5 * np.pi, 0, 0)))

Operator([[-0.70710678+0.j, -0.70710678+0.j],
          [ 0.70710678+0.j, -0.70710678+0.j]],
         input_dims=(2,), output_dims=(2,))
Operator([[-0.70710678+0.j, -0.70710678+0.j],
          [ 0.70710678+0.j, -0.70710678+0.j]],
         input_dims=(2,), output_dims=(2,))
Operator([[ 0.70710678+0.j,  0.70710678+0.j],
          [-0.70710678+0.j,  0.70710678+0.j]],
         input_dims=(2,), output_dims=(2,))
Operator([[ 0.70710678+0.j,  0.70710678+0.j],
          [-0.70710678+0.j,  0.70710678+0.j]],
         input_dims=(2,), output_dims=(2,))

But do $theta$ values outside the declared range make any real sense in quantum computing?
Or is it just a little flaw in Qiskit?
Just in case, the formula for the U3 gate is
$$
mathrm{U3}=
begin{pmatrix}
cos(theta/2) & -mathrm{e}^{ilambda}sin(theta/2) 
mathrm{e}^{iphi}sin(theta/2) & mathrm{e}^{i(phi+lambda)}cos(theta/2) 
end{pmatrix}.
$$

Jonathcraft · Answer

You use the mathematical  representation of the gate to generate something you can apply to your qubit. Nothing breaks if you input $theta$ higher that the range given. We can see this with some examples :
With $theta = 0$ and not thinking about the phase,
$$
U3 = 
begin{pmatrix}
1 & 0 
0 & 1 
end{pmatrix}
$$
With $theta = frac{pi}{2}$ and not thinking about the phase,
$$
U3 = 
begin{pmatrix}
0.7071 & 0.7071 
0.7071 &  0.7071 
end{pmatrix}
$$
With $theta = pi$ and not thinking about the phase,
$$
U3 = 
begin{pmatrix}
0 & 1 
1 &  0 
end{pmatrix}
$$
With $theta = frac{3pi}{2}$ and not thinking about the phase,
$$
U3 = 
begin{pmatrix}
-0.7071 & 0.7071 
0.7071 &  -0.7071 
end{pmatrix}
$$
With $theta = 2pi$ and not thinking about the phase,
$$
U3 = 
begin{pmatrix}
-1 & 0 
0 & -1 
end{pmatrix}
$$
The process then continues alternating a global phase of -1 and 1. As you can see the only thing changing are the pbases and not the complex amplitudes  so there is no problem with the quantum computation.

Why is declared that $0 le theta le pi$ for Qiskit's U3 gate?

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