In singleplayer, server's tick stops upon using a command block, but not upon using a structure block.

How to reproduce:

• Place a command block and a structure block
• Open the debug menu with TPS stats (F3+Alt)
• Use the command block (right click) and see that the ticks are stopped
• Use the structure block (right click) and see that the ticks are not stopped

What I was expecting:

I was expecting to have TPS stopped when I used the structure block.