No, it's just what a 501(c)(3) is: a religious, charitable, scientific, literary, or educational organization, or a handful of other more specialized causes. Note that like a corporation, a 501(c)(3) is allowed to spend a portion of its funds on lobbying, it just can't be the prime focus.
There are other non-profit organization types that are specifically suited for political action. Labor unions are 501(c)(5) and often very political. But most political organizations are regulated under section 527 of the code.
The reason is simple: different codes require different reporting requirements. The 501 codes are heavily scrutinized by the IRS to make sure they are legitimate charitable causes. 527 orgs are overseen by the FEC to make sure that they obey political campaign financing laws. The reporting requirements for both are different.
There are other non-profit organization types that are specifically suited for political action. Labor unions are 501(c)(5) and often very political. But most political organizations are regulated under section 527 of the code.
The reason is simple: different codes require different reporting requirements. The 501 codes are heavily scrutinized by the IRS to make sure they are legitimate charitable causes. 527 orgs are overseen by the FEC to make sure that they obey political campaign financing laws. The reporting requirements for both are different.