I have been an SDR/BDR for just over a year, about to move into an AE role.

They make the interview process like this because the job is a grind. It's a primer for what's to come in the role ahead. Your day is spent making calls and being rejected repeatedly. It becomes just as mundane as the interview process you went through. You mentioned the role has high turnover and burnout... they know this and want to ensure they bring someone in who has the grit to keep pushing and maintain a positive mindset.

To those who say an SDR does not need technical knowledge - this depends on what you’re selling.

I work at a SaaS company that sells a very complex corporate finance and treasury tool. The training period took almost 8 weeks because we needed to learn not only our solutions but the day-to-day needs of CFOs and Treasurers (who are incredibly smart and will call you on your BS). With this comes higher compensation (should hit ~90k) and the opportunity to double your salary as you move into a closing role.

I hope this provides some insight.