Because for most of the XIX century, "republic" became synonymous with massacres, and the violence applied to the peasants created an entrenched opposition to the republic (which ultimately lead to the 2nd empire). The ancien regime was on its last leg and I think it is likely France would have otherwise taken the path to a constitutional monarchy that it started in the early days of the revolution, effectively following what happened in the UK.
The French state declared bankruptcy in 1788 and it was a slow motion disaster. The calling of the Estates General to agree a new constitutional settlement was not the Crown’s preferred way of dealing with the necessity to share more power to get agreement to pay more taxes but they knew a new constitutional settlement was going to happen. The last attempt to keep things somewhat under royal control was the 1787 Assembly of Notables[1]. But even then it was obvious that there was going to be a radical change in government. A great deal more democracy was going to arrive in France, 25 years of war in Europe or no.
This point requires justification. There’s no evidence that democracy would have arrived in France without revolution.