Even if it was 1 to 1 backed by the corporations that claims they are backed by real fiat (which some even came clear about not being 1 to 1 backed anymore so I don't know why they are worth like that) its still not the same with bitcoin. There is always risk of printing more, there is always risk of centralized issues of withdrawing money from the market, and the biggest threat of all there is always an issue of "lol gotcha" of the corporation that reeped the benefits of it and than leave as an exit scam.
Why would anyone prefer stablecoins over bitcoin I don't know, if you want to use regular fiat just use fiat anyway, there is no one stopping you to use dollars for example, that is what many people do, if you want to use bitcoin than use bitcoin but if you use tether for example that is neither as safe as bitcoin nor as accepted as dollars so whats the point.
About five months passed, during this time the idea of creating a stable Libra coin came up, they began to actively discuss this idea and, I see, the general attitude towards stable coins has changed for the better. Yes, and statistics say that the stable USDT coin in terms of trading volume exceeded the trading volume in bitcoins. Cryptocurrency users still began to understand certain advantages and conveniences of stable coins. Of course, stable coins are necessary for people and useful for cryptocurrencies, since they attract attention and interest to it. Stable coins and a common cryptocurrency will occupy each its niche in human financial activity.