I think the common thread with Twilio the sms/sip product and Twilio the CDP / nee Segment is this: businesses outgrow them. Both of them work well for smb and lower midmarket, but as companies grow, become horrendously expensive and essentially strongly encourage migration off. A public company is not a failure, but when your product has a ceiling with your customers, that's painful.
I also had a really annoying experience with Sendgrid post acquisition. I'd used Sendgrid for my first company (as in I personally made the purchase, implemented the apis, and for a long time, was the sole and then admin account). I went to use it for my next company pre website launch and they froze my new account and their customer service was a pita. To be fair, the site wasn't up, but I needed the ability to send emails to publish the site (it's a crucial part of new account flow.) They wouldn't allow me to use sendgrid even though I was happy to share my linkedin, my previous history with their company, etc. We're happy sendinblue customers.
I also had a really annoying experience with Sendgrid post acquisition. I'd used Sendgrid for my first company (as in I personally made the purchase, implemented the apis, and for a long time, was the sole and then admin account). I went to use it for my next company pre website launch and they froze my new account and their customer service was a pita. To be fair, the site wasn't up, but I needed the ability to send emails to publish the site (it's a crucial part of new account flow.) They wouldn't allow me to use sendgrid even though I was happy to share my linkedin, my previous history with their company, etc. We're happy sendinblue customers.