A safeguard WAS put into place. We call it the Electoral College (although it is not named as such in the Constitution). It failed miserably at that goal.
The original vision when the Electoral College system was devised had three aims:
- To prevent political parties from dominating politics.
- To prevent a populist from getting elected to office.
- To "handicap" larger states so smaller states could still have a voice.
To prevent political parties, the original text of the Constitution required each member of the Electoral College to cast two votes for President (one of which could not be for someone from that elector's home state (to prevent the "favorite son" problem). The top vote-getter would be the President, and the 2nd-place vote-getter would be the Vice President.
The idea here is that the President and Vice President would likely be from different parties, since nobody runs for 2nd place. Constitutionally, the Vice President is the head of the Senate, so the thinking was that the differing political ideologies between them would force them to work together to achieve some compromise or consensus to get things done. This plan went sour very, very quickly with the elections of 1796 and 1800 respectively.
John Adams and Thomas Jefferson were bitter political enemies. In 1796 with Adams as President, Jefferson leveraged his position as Vice President to attack Adams' policies, and the Adams administration turned out to be a very dysfunctional government.
The election of 1800 was even worse. Both parties attempted to gerrymander their electoral districts to sway the vote, and the shenanigans resulted in a tie. If nobody gets a majority in the Electoral College, the Constitution says that the House of Representatives then votes to appoint the President. Both parties tried to collude with other factions within the House with endless ties as the end result. It took 36 ballots to finally break the tie, with Jefferson and Adams swapping their President and Vice President seats.
Because the two back-to-back election cycles were such a colossal disaster, the 12th Amendment was passed, subtly but fundamentally changing how the Electoral voting system worked. Under the 12th Amendment, electors still cast two ballots, but they are marked specifically one for President and one for Vice President. This change basically abandoned the idea that the runner-up would be from the opposing party, and the President and Vice President have run together strategically on the same party ticket ever since.
The idea that we could have a truly bipartisan government is a great idea in theory, but history has shown us that it was completely unworkable in practice (at least, with the system they tried anyway).
In my personal opinion, politics always devolves into the worst form of tribalism no matter how great or small the stakes. In a naive, idealized form of democracy, elected representatives carry forward the values of their constituents in national policymaking. In reality, however, most elections are not about voting for your own values; they're about voting against the other guy's values, because those values will destroy the country. Political parties are the inevitable result of people banding together to prevent the other side from "winning", rather than a mechanism for carrying forward one's own ideals. This was as true in the 18th century as it is today.
This isn't just an American thing; you see this in every democratic country in the world. Politics being what it is, political parties -- no matter how much we might wish it weren't so -- are an inseparable property of a representative government.