WPF多线程更新UI与使用inotifypropertychanged有什么区别

最近在自学wpf多线程编程，经过2天的秃头后，终于理清了即使我开再多的线程，只要我调用BeginInvoke或者invoke，始终会回到主线程中运行，导致界面卡顿，那么基于下面的demo，我有一个疑问
这是xaml代码

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        mc:Ignorable="d"
        Title="WindowThd" Height="150" Width="400">
    <Grid>
        <StackPanel>
            <Label x:Name="lblHello" Height="25" Content="{Binding Path=MyStr}"/>
            <Button Name="btnThd" Click="btnThd_Click" >Test</Button>
        </StackPanel>
    </Grid>
</Window>

这是后端代码

    public partial class MainWindow : Window
    {
        Para myPara = new Para();
        public MainWindow()
        {
            this.DataContext = myPara;
            InitializeComponent();
        }
        private void ModifyUI()
        {
            for (int i = 0; i < 5; i++)
            {                
                myPara.MyStr = "Test" + DateTime.Now.ToString();
                Thread.Sleep(1000);
            }
            //this.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (Action)delegate()
            //{
            //    Thread.Sleep(1000);
            //    lblHello.Content = "Test" + DateTime.Now.ToString();
            //});
        }
        private void btnThd_Click(object sender, RoutedEventArgs e)
        {
            Thread thread = new Thread(ModifyUI);
            thread.IsBackground = false;
            thread.Start();
        }
    }
    public class Para : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        protected void OnPropertyChanged(string propertyName) => 
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        private string myStr;
        public string MyStr 
        {
            get { return myStr; }
            set { myStr = value;OnPropertyChanged(nameof(MyStr));}
        }
    }

测试功能就是点击按钮后新建一个线程，调用一个函数每过一段时间刷新一个字符串显示
这个程序本身没啥意义，主要是我在开始操作不当把sleep放到invoke里了导致卡顿，后来我通过inotifypropertychanged绑定后就没用invoke了，所以我有个疑问，如果直接通过bangding，那invoke有什么使用的意义呢？