Whether stuff like Bluetooth, 3.5mm headphone jacks, or external DACs are convenient is purely subjective.
Personally, I prefer to use a built in 3.5mm jack on my phone and wired iems when I’m out and about. My old iPhone 6 was the last iPhone to use a 3.5mm jack and I loved it. Minimum amount of kit to carry and charge, and it sounded good.
When the time came to replace the phone, I considered another iPhone, but they no longer use the 3.5mm jack. A new iPhone would mean using a dongle or Bluetooth IEMs. However, I wasn’t FORCED to go down this route. There’s still plenty of other phone manufacturers who include a 3.5mm jack on their phones.
I chose an Oppo Find X3 Lite, which has a 3.5mm jack, and my IEMs sound great out of it. It also works great with Bluetooth headphones and I can also use a dongle with it too if I want.
If a phone manufacturer stops offering a 3.5mm jack, I’ll shop elsewhere, it’s not a problem. If other people prefer to use dongles/Bluetooth, then that’s their choice, they know what works for them.