One needs to consider why the usage of automated responses.
Is it engagement drive? Is it inflating metrics? Is it manipulation? I do not see a scenario where it is purely done because someone wants to be nice.
1. Get more followers. A lot of people see follower count as a goal that matters to them. Replying to high follower counts may earn you a follow from them or from someone reading their replies who doesn't catch that you are a bot.
2. Establish account credibility. Does Twitter's algorithm rank posts higher from accounts that have a long history of engaging with other accounts? I don't know for sure, neither do they but they may believe it's worth trying anyway.
3. Accounts for sale. There's a market for used Twitter accounts with plenty of realistic looking activity. Maybe these spammers are building inventory.
1. Get more followers. A lot of people see follower count as a goal that matters to them. Replying to high follower counts may earn you a follow from them or from someone reading their replies who doesn't catch that you are a bot.
2. Establish account credibility. Does Twitter's algorithm rank posts higher from accounts that have a long history of engaging with other accounts? I don't know for sure, neither do they but they may believe it's worth trying anyway.
3. Accounts for sale. There's a market for used Twitter accounts with plenty of realistic looking activity. Maybe these spammers are building inventory.